Svein Samdal

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2016). Rotational Spectrum, Conformational Composition, Intramolecular Hydrogen Bonding, and Quantum Chemical Calculations of Mercaptoacetonitrile (HSCH2C≡N), a Compound of Potential Astrochemical Interest. Journal of Physical Chemistry A. ISSN 1089-5639. 120(12), p. 1992–2001. doi: 10.1021/acs.jpca.6b01600. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2016). Microwave and Quantum Chemical Study of Intramolecular Hydrogen Bonding in 2-Propenylhydrazine (H2C=CHCH2NHNH2). Journal of Physical Chemistry A. ISSN 1089-5639. 120(3), p. 407–416. doi: 10.1021/acs.jpca.5b11141. Full text in Research Archive Show summary

  The microwave spectrum of 2-propenylhydrazine (H2C=CHCH2NHNH2) was studied in the 12 – 61 and 72 – 123 GHz spectral regions. A variety of intramolecular hydrogen bonds between one or more of the hydrogen atoms of the hydrazino group and the -electrons are possible for this compound. Assignments of the spectra of four conformers, all of which are stabilized with intramolecular hydrogen bonds are reported. One hydrogen bond exists in two of these conformers, whereas the -electrons are shared by two hydrogen atoms in the two other rotamers. Vibrationally excited states spectra were assigned for three of the four conformers. The internal hydrogen bonds are weak, probably in the 3 – 6 kJ/mol range. A total of about 4400 transitions were assigned for these four forms. The microwave work was guided by quantum chemical calculations at the B3LYP/cc-pVTZ and CCSD/cc-pVTZ levels of theory. These calculations indicated that as many as 18 conformers may exist for 2-propenylhydrazine and 11 of these have either one or two intramolecular hydrogen bonds. The four conformers detected in this work are among the rotamers with the lowest CCSD electronic energies. The CCSD method predicts rotational constants that are very close to the experimental rotational constants. The B3LYP calculations yielded quartic centrifugal distortion constants that deviated considerably from their experimental counterparts in most cases. The calculation of vibration-rotation constants and sextic centrifugal distortion constants by the B3LYP method were generally found to be in poor agreement with the corresponding experimental constants.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2016). Microwave and Quantum Chemical Study of Intramolecular Hydrogen Bonding in 2-Propynylhydrazine (HC≡CCH2NHNH2). Journal of Physical Chemistry A. ISSN 1089-5639. 120(23), p. 4071–4078. doi: 10.1021/acs.jpca.6b03796. Full text in Research Archive
• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2015). Conformational Properties of cis- and trans-N-Cyclopropylformamide Studied by Microwave Spectroscopy and Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 119(14), p. 3375–3383. doi: 10.1021/acs.jpca.5b00542. Full text in Research Archive Show summary

  The microwave spectra of cis- and trans-N-cyclopropylformamide, C3H5NHC(=O)H, have been investigated in the 31 – 123 GHz spectral region at room temperature. Rotational isomerism about the Cring‒N bond is possible for both cis and trans. MP2/cc-pVTZ and CCSD/cc-pVTZ calculations indicate that there are two conformers in the case of cis, called Cis I and Cis II, while only one rotamer, denoted Trans, exists for trans-N-cyclopropylformamide. The quantum chemical methods predict that Cis I has an electronic energy that is 8 – 9 kJ/mol higher than the energy of Cis II. The CCSD H‒Cring‒N‒H dihedral angle is 0.0º in Cis I, 93.0º in Cis II and 79.9º in Trans. The CCSD and MP2 calculations predict a slightly non-planar structure for the amide moiety in both Trans and Cis II, whereas Cis I is computed to have a planar amide group bisecting the cyclopropyl ring. Surprisingly, the MP2 and CCSD methods predict practically the same energy for Trans and Cis II. The spectra of Cis II in the ground state and in two vibrationally excited states were assigned, while the spectrum of Cis I was not found presumably because of a low Boltzmann population due to a relatively large energy difference (8 – 9 kJ/mol). The spectra of the ground vibrational state and seven vibrationally excited states of Trans, were assigned. Vibrational frequencies of several of the excited state of both Cis II and Trans were determined by relative intensity measurements. The experimental and CCSD rotational constants are in satisfactory agreement. The MP2 values of the quartic centrifugal distortion constants of both species are in relatively poor agreement with their experimental counterparts. The MP2 vibration-rotation constants and sextic centrifugal distortion constants have little resemblance with the corresponding experimental values.

• Samdal, Svein; Møllendal, Harald & Carles, Sophie (2015). Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH2C≡N), a Compound of Potential Astrochemical Interest. Journal of Physical Chemistry A. ISSN 1089-5639. 119, p. 9070–9077. doi: 10.1021/acs.jpca.5b05285. Full text in Research Archive Show summary

  The rotational spectrum of cyanomethyl formate (HC(O)OCH2C≡N) has been recorded in the 12 – 123 GHz spectral range. The spectra of two conformers were assigned. The rotamer denoted I has a symmetry plane and two out-of plane hydrogen atoms belonging to the cyanomethyl (CH2CN) moiety. In the conformer called II, the cyanomethyl group is rotated 80.3º out of this plane. Conformer I has an energy that is 1.4(6) kJ/mol lower than the energy of II according to relative intensity measurements. A large number of rotational transitions have been assigned for the ground and vibrationally excited states of the two conformers and accurate spectroscopic constants have been obtained. These constants should predict frequencies of transitions outside the investigated spectral range with a very high degree of precision. It is suggested that cyanomethyl formate is a potential interstellar compound. This suggestion is based on the fact that its congener methyl formate (HC(O)OCH3) exists across a large variety of interstellar environments and the fact that cyanides are very prevalent in the Universe. The experimental work has been augmented by high-level quantum chemical calculations. The CCSD/cc-pVQZ calculations are found to predict structures of the two forms that are very close to the Born-Oppenheimer equilibrium structures. MP2/cc-pVTZ predictions of several vibration-rotation interaction constants were generally found to be rather inaccurate. A gas-phase reaction between methyl formate and the cyanomethyl radical CH2CN to produce a hydrogen atom and cyanomethyl formate was mimicked using MP2/cc-pVTZ calculations. It was found that this reaction is not favored thermodynamically. It is also conjectured that the possible formation of cyanomethyl formate might be catalyzed and take place on interstellar particles.

• Samdal, Svein; Møllendal, Harald; Reine, Simen Sommerfelt & Guillemin, Jean-Claude (2015). Ring planarity problem of 2-oxazoline revisited using microwave spectroscopy and quantum chemical calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 119(20), p. 4875–4884. doi: 10.1021/acs.jpca.5b02528. Full text in Research Archive Show summary

  In a previous infrared, Raman and microwave spectroscopic work,1 it was claimed that 2-oxazoline has a planar ring equilibrium conformation and the ring-puckering potential function V(z) = 22.2(z4 + 1.31z2)cm‒1, where z is a dimensionless reduced coordinate, was derived. This function reproduces poorly the rotational constants of the lowest and decisive puckering states. The microwave spectrum has been reinvestigated and largely extended to include more than 4600 transitions of the ground state and six excited states of the ring-puckering vibration allowing accurate centrifugal distortion constants to be obtained for the first time. A new potential function V(z) = 38.8(z4 ‒ 0.65z2)cm‒1 has been determined. This function yields much better agreement between calculated and observed rotational constants, especially for the lowest puckering states, than the previous function and predicts a nonplanar ring equilibrium conformation. The barrier to ring planarity is determined to be 49(8) J/mol. The ground-state energy level is 35 cm‒1 above the barrier maximum. Theory predicts that three of the five Watson centrifugal distortion constants, JK, K, and K should vary with the puckering state, whereas J and J should be unaffected. It was found that JK and K indeed behave in the expected manner, while deviations were seen for the three other centrifugal distortion constants. The ab initio methods HF, MP2, CCSD, CCSD(T), CCSD(T)-F12 with large basis sets as well as several DFT methods were used in an attempt to reproduce the low experimental barrier to planar ring. Only the MP2 method yielded a satisfactory prediction of the barrier. The CCSD and the CCSD(T) calculations predict a planar ring, whereas the energy differences between a planar and a nonplanar ring obtained in the CCSD(T)-F12 computations are so small that a definite conclusion cannot be drawn

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2015). Microwave and quantum-chemical study of conformational properties and intramolecular hydrogen bonding of 2-hydroxy-3-butynenitrile (HC≡CCH(OH)C≡N). Journal of Physical Chemistry A. ISSN 1089-5639. 119(4), p. 634–640. doi: 10.1021/jp5112923. Full text in Research Archive Show summary

  The microwave spectra of 2-hydroxy-3-butynenitrile (HC≡CCH(OH)C≡N) and a deuterated species, HC≡CCH(OD)C≡N, have been investigated in the 38 – 120 GHz spectral region. Three rotameric forms each stabilized by intramolecular hydrogen bonds are possible for this compound. The hydrogen atom of the hydroxyl group is bonded to the -electrons of the alkynyl group in one of these conformers, to the -electrons of the cyano group in the second rotamer, and to both these groups simultaneously in the third conformer. The microwave spectrum of the parent and deuterated species of last-mentioned form has been assigned and accurate values have been determined for the rotational and quartic centrifugal distortion constants of these species. The spectra of two vibrational excited states of this conformer have also been assigned and their frequencies determined by relative intensity measurements. Quantum chemical calculations at the MP2/cc-pVTZ and CCSD/cc-pVQZ have been performed to assist the microwave work. The theoretical predictions are generally found to be in good agreement with observations.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2015). Microwave and quantum chemical study of the hydrazino group as proton donor in intramolecular hydrogen bonding of (2-Fluoroethyl)hydrazine (FCH2CH2NHNH2). Journal of Physical Chemistry A. ISSN 1089-5639. 119, p. 9252–9261. doi: 10.1021/acs.jpca.5b06095. Full text in Research Archive Show summary

  The microwave spectrum of (2-fluoroethyl)hydrazine (FCH2CH2NHNH2) has been studied in the 11 – 123 GHz spectral region in order to investigate the ability of the hydrazino group to form intramolecular hydrogen bonds acting as a proton donor. This group can participate both in five-member and in six-member internal hydrogen bonds with the fluorine atom. The spectra of four conformers were assigned and the rotational and centrifugal distortion constants of these rotameric forms were determined. Two of these conformers have five-member intramolecular hydrogen bonds while the two other forms are without this interaction. The internal hydrogen bonds in the two hydrogen-bonded forms are assumed to be mainly electrostatic in origin because the N‒H and C‒F bonds are nearly parallel and the associated bond moments are antiparallel. This is the first example of a gas-phase study of a hydrazine where the hydrazino functional group acts as a proton donor in weak intramolecular hydrogen bonds. Extensive quantum chemical calculations at the B3LYP/cc-pVTZ, MP2/cc-pVTZ, and CCSD/cc-pVQZ levels of theory were accompanying and guiding the experimental work. These calculations predict the existence of no less than 18 conformers, spanning a CCSD internal energy range of 15.4 kJ/mol. Intramolecular hydrogen bonds are predicted to be present in seven of these conformers. Three of these forms have six-member hydrogen bonds, while four have five-member hydrogen bonds. The three lowest-energy conformers have five-member internal hydrogen bonds. The spectrum of the conformer with the lowest energy was not assigned because it has a very small dipole moment. The CCSD relative energies of the two hydrogen-bonded rotamers whose spectra were assigned, are 1.04 and 1.62 kJ/mol, respectively, whereas the relative energies of the two conformers with assigned spectra and no hydrogen bonds have relative energies of 6.46 and 4.89 kJ/mol.

• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2014). Microwave spectrum, conformational composition, and dipole moment of (fluoromethyl)cyclopropane (C3H5CH2F). Journal of Physical Chemistry A. ISSN 1089-5639. 118(12), p. 2344–2352. doi: 10.1021/jp500985a. Full text in Research Archive Show summary

  ABSTRACT: The microwave spectrum of (fluoromethyl)cyclopropane, C3H5CH2F, has been investigated in the whole 12 – 75.6 GHz spectral range. Many measurements were also performed in the 75.6 – 120 GHz region. The spectra of two conformers were assigned. The H‒C‒C‒F chain of atoms is antiperiplanar in the conformer denoted ap and synclinal in the sc rotamer. The sc conformer has a lower energy than ap. The internal energy difference was determined to be Eap – Esc = 1.7(8) kJ/mol from relative intensity measurements. The spectra of the ground vibrational state and 7 vibrationally excited states belonging to two different normal modes were assigned for sc. The frequencies of these two modes were determined by relative intensity measurements. The dipole moment of this conformer was determined to be µa= 5.520(17), µb= 3.475(29), µc= 0.35(13), and µTOT= 6.532(40) × 10‒30 C m [1.958(12) debye]. The spectrum of the ground vibrational state was assigned for ap. The microwave work was supported by quantum chemical calculations at the CCSD/cc-pVQZ, MP2/cc-pVTZ, and B3LYP/cc-pVTZ levels of theory.

• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2014). Synthesis, microwave spectrum, quantum chemical calculations, and conformational composition of the novel compound cyclopropylethylidinephosphine (C3H5CH2C≡P). Journal of Physical Chemistry A. ISSN 1089-5639. 118(43), p. 9994–10001. doi: 10.1021/jp508411z. Full text in Research Archive Show summary

  ABSTRACT: The synthesis of the novel compound cyclopropylethylidynephosphine (C3H5CH2C≡P) and its microwave spectrum are reported together with quantum chemical calculations. The spectrum, which reveals the existence of two conformers, has been recorded in the 38 – 109 GHz spectral range at room temperature. The H‒C‒CH2‒C chain of atoms is synclinal in one rotamer denoted sc, and antiperiplanar in the second conformer called ap. The spectra of the ground vibrational state and two vibrationally excited states were assigned for each rotamer. The vibrational frequencies of these excited states were determined by relative intensity measurements. Relative intensity measurements were also conducted to determine the energy difference between ap and sc. The latter conformer was found to be the lower-energy form and Eap – Esc was determined to be 0.9(4) kJ/mol. The microwave study has been augmented by quantum chemical calculations at the CCSD/cc-pVQZ and MP2/cc-pVTZ levels of theory. The CCSD predictions were generally in good agreement with experiment, while somewhat mixed results were obtained in the MP2 calculations.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2014). Microwave spectrum and conformational composition of(Azidomethyl)cyclopropane(C3H5CH2N3). Journal of Physical Chemistry A. ISSN 1089-5639. 118, p. 6971–6978. doi: 10.1021/jp506261a. Full text in Research Archive Show summary

  The microwave spectrum of (azidomethyl)cyclopropane, C3H5CH2N3, has been investigated in the 26 – 90 GHz spectral range at a temperature of about ‒30 ºC. Five rotameric forms of this compound, whose spectra can be distinguished by microwave spectroscopy, may exist. The spectra of three of them denoted III, IV, and V were assigned. The ground vibrational state spectra of III and V were assigned, while the ground and six vibrationally excited states were assigned for IV. These three rotamers all have a synclinal orientation of the H‒C‒C‒N chain of atoms, while the C‒C‒N‒N link is either + or ‒synclinal, or antiperiplanar. Conformer IV, having synclinal orientation of the two said dihedral angles, was found to have the lowest energy by relative intensity measurements. Rotamer V has an energy that is 1.6(6) kJ/mol higher than the energy of IV, while the energy of III is 2.1(6) kJ/mol higher than the energy of IV. Quantum chemical calculations were performed at the MP2/cc-pVTZ and CCSD/cc-pVTZ levels of theory. The rotational constants obtained in the CCSD calculations are in good agreement with the experimental rotational constants, while the MP2 centrifugal distortion constants are generally in poorer agreement with their experimental counterparts.

• Møllendal, Harald; Samdal, Svein; Gauss, Jürgen & Guillemin, Jean-Claude (2014). Synthesis, microwave spectrum, quantum chemical calculations, and conformational composition of a novel primary phosphine, cyclopropylethynylphosphine,(C3H5C≡CPH2). Journal of Physical Chemistry A. ISSN 1089-5639. 118(40), p. 9419–9428. doi: 10.1021/jp506169g. Full text in Research Archive Show summary

  The microwave spectrum of cyclopropylethynylphosphine, C3H5C≡CPH2, has been investigated in the 26 – 120 GHz spectral region. The spectrum is dominated by very rich and complex a-type R-branch pile-ups. There must be insignificant steric interaction between the phosphino group and the cyclopropyl ring due to the long distance between these two groups. However, the phosphino group does not undergo free or nearly free internal rotation. Instead, the spectra of two distinct conformers were assigned. Both these two forms have CS symmetry. The symmetry plane bisects the cyclopropyl ring and the phosphino group in both conformers and the lone electron pair of the phosphino group points in opposite directions in the two rotamers. The energy difference between the two forms was determined to be 1.9(6) kJ/mol. A simple model that takes into consideration the interaction of the lone electron pair of the phosphino group with the -electrons of the ethynyl group and the Walsh electrons of the cyclopropyl ring is able to give a qualitative explanation of the observation of two conformers and the nonexistence of free rotation of the phosphino group. The MW work was augmented by quantum chemical calculations using second-order Møller-Plesset perturbation and coupled cluster theory with results that are in good agreement with experiments.

• Samdal, Svein; Grønås, Terje; Møllendal, Harald & Guillemin, Jean-Claude (2014). Microwave Spectrum and Conformational Properties of 4-Isocyano-1-butene (H2C=CHCH2CH2N≡C). Journal of Physical Chemistry A. ISSN 1089-5639. 118(8), p. 1413–1419. doi: 10.1021/jp4122134. Full text in Research Archive Show summary

  The microwave spectrum of 4-isocyano-1-butene (H2C=CHCH2CH2NC) has been investigated in the 35 – 80 GHz spectral region. Selected measurements have also been made outside this spectral range. Rotation about the ‒CH‒CH2‒ and ‒CH2‒CH2‒ single bonds may produce rotational isomerism resulting in five conformers. The spectra of three of them, denoted I, III, and IV, have been assigned. In conformer I, the C=C‒C‒C link of atoms is +anticlinal and the C‒C‒C‒N chain is antiperiplanar. In III, the two links of atoms are +anticlinal and +synclinal, whereas in IV, the two chains are synperiplanar and antiperiplanar, respectively. Conformer I was found to have the lowest energy of the three forms by relative intensity measurements. These measurements yielded EIII – EI = 1.1(7) kJ/mol, and EIV – EI = 2.9(7) kJ/mol for the internal energy differences. The microwave study was augmented by quantum chemical calculations at the CCSD/cc-pVQZ and MP2/cc-pVTZ levels of theory. Good agreement between experimental and theoretical results was seen in most cases.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2014). Microwave Spectrum and Intramolecular Hydrogen Bonding of 2-Isocyanoethanol (HOCH2CH2NC). Journal of Physical Chemistry A. ISSN 1089-5639. 118(17), p. 3120–3127. doi: 10.1021/jp502212n. Full text in Research Archive Show summary

  ABSTRACT: The microwave spectrum of 2-isocyanoethanol (HOCH2CH2NC) has been investigated in the 12 – 120 GHz spectral range. The assignment of this spectrum was severely complicated by the rapid transformation of 2-isocyanoethanol into its isomer 2-oxazoline, which has a rich and strong spectrum. This process appeared both in a gold-plated microwave cell and in a brass cell and is presumed to be catalyzed by metals or traces of base. The spectrum of one conformer was ultimately assigned. This form is stabilized by an intramolecular hydrogen bond between the hydroxyl group and the isocyano group and is the first gas-phase study ever of this kind of hydrogen bonding. The distance between the hydrogen atom of the hydroxyl group and the nitrogen and carbon atoms are as long as 256 and 298 pm, respectively, indicating that covalent contribution to the hydrogen bond is minimal. Electrostatic forces are much more important because the O‒H and N≡C bonds are almost parallel and the corresponding bond moments are practically antiparallel. The microwave work has been augmented by quantum chemical calculations at the CCSD(T)/cc-pVTZ and MP2/cc-pVTZ levels of theory. Results of these calculations are generally in good agreement with experimental findings.

• Tverdova, Natalya V; Girichev, Georgiy v & Samdal, Svein (2013). The molecular structures of tris(dipivaloylmethanato)chromium and tris(dipivaloylmethanato)cobalt determined by gas electron diffraction and density functional theory calculations. Structural Chemistry. ISSN 1040-0400. 24(3), p. 891–900. doi: 10.1007/s11224-013-0205-5. Full text in Research Archive
• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2013). Microwave Spectrum, Conformational Properties, and Dipole Moment of Cyclopropylmethyl lsocyanide (C3H5CH2NC). Journal of Physical Chemistry A. ISSN 1089-5639. 117(24), p. 5073–5081. doi: 10.1021/jp403374k. Full text in Research Archive Show summary

  ABSTRACT: The microwave spectrum of cyclopropylmethyl isocyanide, C3H5CH2NC, has been investigated in the 25−75 GHz spectral range. The spectra of two conformers were assigned. The H−C−C−N chain of atoms is antiperiplanar in the conformer denoted ap and synclinal in the sc rotamer. The scconformer tends to be slightly more stable than the ap form. The internal energy difference was determined to be Eap − Esc = 0.2(7) kJ/mol from relative intensity measurements. The spectra of the ground vibrational state and six vibrationally excited states belonging to two different normal vibrations were assigned for sc. The frequencies of these two modes were determined by relative intensity measurements. The dipole moment of this conformer was determined to be μa = 12.16(6), μb = 5.91(4), μc = 0 (preset), and μtot = 13.52(6) × 10−30 C m [4.05 (2) debye]. The spectra of the ground and of two vibrationally excited states belonging to the torsion and lowest bending vibration were assigned for ap. The microwave work was supported by quantum chemical calculations at the CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory. Most, but not all, of the theoretical predictions are in good agreement with experiment.

• Samdal, Svein; Grønås, Terje; Møllendal, Harald & Guillemin, Jean-Claude (2013). Microwave Spectrum and Conformational Properties of 4-Isocyano-1-butyne (HC≡CHCH2CH2N≡C). Journal of Physical Chemistry A. ISSN 1089-5639. 117(40), p. 10304–10310. doi: 10.1021/jp407126x. Full text in Research Archive Show summary

  The microwave spectrum of 4-isocyano-1-butyne (HC≡CCH2CH2N≡C) has been investigated in the 12.4 – 77.6 GHz spectral region. The spectra of two rotamers denoted ap and sc were assigned. ap has an antiperiplanar arrangement for the C‒C‒C‒N chain of atoms, whereas sc has synclinal conformation for this link. The ground state spectrum and three vibrationally excited state spectra of the lowest torsional vibration were assigned for ap, while the ground vibrational state spectrum was assigned for sc. The C‒C‒C‒N dihedral angle was found to be 64.5(30)º in sc and exactly 180º in ap. ap was determined to be 2.9(6) kJ/mol lower in energy than sc from relative intensity measurements. The microwave study has been augmented with ab initio and DFT calculations employing the CCSD(T), MP2, and B3LYP methods with the cc-pVTZ basis set. A Natural Bond Order analysis has also been performed. Most, but not all, of the quantum chemical predictions agree satisfactorily with the experimental results.

• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2013). Synthesis, Microwave Spectrum, and Conformational Properties of 2-Fluoroethyl Azide (FCH2CH2N3). Journal of Physical Chemistry A. ISSN 1089-5639. 117, p. 1935–1940. doi: 10.1021/jp312227t. Full text in Research Archive Show summary

  ABSTRACT: A novel synthesis producing neat 2-fluoroethylazide (FCH2CH2N3) is described. A conformational analysis using microwave spectroscopy augmented by quantum chemical calculations at the CCSD(T)/cc-pVTZ, B3LYP/aug-cc-pVTZ, and B3LYP/cc-pVTZ levels of theory has been performed for this compound. The spectra of the ground vibrational state and two vibrationally excited states of one rotameric form were assigned. A large number of transitions were assigned and very accurate values were obtained for the rotational and quartic centrifugal distortion constants. The identified conformer has synclinal orientations for the F‒C‒C‒N and C‒C‒N‒N chains of atoms bringing the fluorine atom and the azido group into close proximity. It is concluded from consideration of absolute intensities that this conformer is indeed the preferred form of the molecule in accord with the theoretical calculations. The experimental and CCSD(T) rotational constants are in very good agreement, whereas much larger discrepancies were seen for the experimental and B3LYP quartic centrifugal distortion constants.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2012). Microwave Spectrum and Conformational Composition of 3-Fluoropropionitrile (FCH2CH2CN). Journal of Physical Chemistry A. ISSN 1089-5639. 116(3), p. 1015–1022. doi: 10.1021/jp210932k. Full text in Research Archive Show summary

  Abstract The microwave spectrum of 3-fluoropropionitrile, FCH2CH2C≡N, has been investigated in the whole 17 – 75 GHz spectral region. Selected portions of the spectrum in the 75 – 95 GHz have also been recorded. The microwave spectra of the ground state as well as of three vibrationally excited states of each of two conformers have been assigned. The spectra of the vibrationally excited states belong to the lowest torsional and bending vibrations. The F‒C‒C‒C chain of atoms is exactly antiperiplanar in one of these rotamers and synclinal in the second conformer. The F‒C‒C‒C dihedral angle is 65(2)º in the synclinal form. The energy difference between the two forms has been obtained from relative intensity measurements performed on microwave transitions. It was found that the antiperiplanar conformer is more stable than the synclinal form by 1.4(5) kJ/mol. It is argued that the gauche effect is a significant force in this compound. Quantum chemical calculations at the high CCSD(full)/cc-pVTZ, MP2(full)/cc-pVTZ, and B3LYP/cc-pVTZ levels of theory have been performed. Most, but not all, of the theoretical predictions are in good agreement with experiment.

• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2012). Microwave spectra and barriers to internal rotation of Z- and E-1-propenyl isocyanide. Journal of Physical Chemistry A. ISSN 1089-5639. 116, p. 8833–8839. doi: 10.1021/jp304227u. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Bunkan, Arne Joakim Coldevin & Guillemin, Jean-Claude (2012). Synthesis and Microwave Spectrum of Vinyl Isoselenocyanate (H2C=CHNCSe), a Compound with a Quasi linear CNCSe Chain. Journal of Physical Chemistry A. ISSN 1089-5639. 116(16), p. 4074–4081. doi: 10.1021/jp301803z. Full text in Research Archive Show summary

  The first a,b-unsaturated isoselenocyanate, vinyl isoselenocyanate (H2C=CHNCSe), has been synthesized and its microwave spectrum has been investigated in the 11.5 – 77.0 GHz spectral range. The microwave work has been augmented by quantum chemical calculations using four different methods, CCSD(T), CCSD, B3LYP, and M062X, with the cc-pVTZ basis set. It is generally assumed that two rotamers having the isoselenocyanide group in an antiperiplanar or a synperiplanar position may exist for this compound. However, these four methods all predict that there is only one rotameric form of the molecule, namely, the antiperiplanar form. The CNC angle of the antiperiplanar rotamer is calculated to vary from 151 to 170º depending on the quantum chemical methodology. CCSD(T) and B3LYP potential functions of the in-plane CNC bending vibrations were calculated. These functions have one shallow minimum corresponding to the antiperiplanar form. The spectra of the ground and of one vibrationally excited state of this rotamer were assigned. Spectral searches for the synperiplanar form were performed but it was not found, and must have a relatively high energy, if it exists at all. The vibrationally excited state is presumably the lowest in-plane bending vibration of the CNC angle. Relative intensity measurements yielded a very low frequency of 18(25) cm‒1 for this vibration. The large-amplitude vibration of this mode suggests that this compound should rather be regarded as having a quasi-linear CNCSe link of atoms than a rigid, bent antiperiplanar form.

• Møllendal, Harald & Samdal, Svein (2012). Microwave Spectra, Planarity, and Conformational Preferences of cis- and trans-N-Vinylformamide. Journal of Physical Chemistry A. ISSN 1089-5639. 116(49), p. 12073–12081. doi: 10.1021/jp309552m. Full text in Research Archive Show summary

  The microwave spectra of a mixture of cis- and trans-H‒N‒C‒O forms of N-vinylformamide, (H2C=CHNHC(=O)H) have been measured at room temperature in the 18 – 75 GHz spectral range. The spectra of two forms were assigned. The first of these forms has a cis arrangement for the H‒N‒C‒O chain of atoms, whereas the second form has a trans arrangement. The C‒C‒N‒C chain of atoms is antiperiplanar (180º) in both forms. The inertial defect of the ground vibrational state of cis is ‒0.142(5) × 10‒20 u m2, whereas this parameter is ‒0.087098(26) × 10‒20 u m2 for trans. It is concluded that the equilibrium structures of both cis and trans are completely planar. The dipole moment determined from Stark effect measurements is a = 9.96(8), b = 2.22(3), c = 0 (by symmetry), and tot = 10.20(8) × 10‒30 C m [3.06(2) D], for cis, while a = 7.64(16), b = 9.24(10), c = 0 (by symmetry), and tot = 12.0(2) × 10‒30 C m [3.59(5) D] for trans. The spectrum of one vibrationally excited state, presumably the first excited state of the torsion about the C‒N bond of cis, was assigned and the frequency of this state was determined to be 76(15) cm‒1 by relative intensity measurements. The spectra of two vibrationally excited states of trans were assigned. These states are assumed to be the first excited state of the torsion about the C‒N bond, and a low bending vibration. Relative intensity measurements yielded 101(20) and ca 300 cm‒1, respectively, for the frequencies of these normal vibrations. Accurate values of the quartic centrifugal distortion constants, the dipole moments, and the vibration-rotation constants have been obtained for both cis and trans. The experimental work has been augmented by high-level quantum chemical calculations at the B3LYP/cc-pVTZ and CCSD(T)/cc-pVTZ levels of theory. The theoretical calculation performed without symmetry restrictions correctly predict that cis and trans are both planar. The CCSD(T) rotational constants are in excellent agreement with their experimental counterparts, whereas the B3LYP quartic centrifugal distortion constants and the vibration-rotation constants are in fairly good agreement with experiments. The CCSD(T) dipole moments deviate more than expected from the experimental dipole moments. It is estimated that further conformers of cis and trans must be at least 4 kJ/mol higher in energy.

• Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2011). Microwave Spectrum and Conformational Composition of 2-Fluoroethylisocyanide. Journal of Physical Chemistry A. ISSN 1089-5639. 115(33), p. 9192–9198. doi: 10.1021/jp205024s. Full text in Research Archive Show summary

  Abstract The microwave spectrum of 2-fluoroethylisocyanide, FCH2CH2N≡C, has been investigated in the whole 50 – 120 GHz spectral region. Selected portions of the spectrum in the 18 – 50 GHz have also been recorded. The microwave spectra of the ground state as well as of vibrationally excited states of two conformers have been assigned. Accurate spectroscopic constants have been derived from a large number of microwave transitions. The F‒C‒C‒N chain of atoms is antiperiplanar in one of these rotamer and synclinal in the second conformer. The energy difference between the two forms has been obtained from relative intensity measurements. It was found that the synclinal conformer is favored over the antiperiplanar form by 0.7(5) kJ/mol. Quantum chemical calculations at the high CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory have been performed. Most, but not all, of the spectroscopic constants predicted in these calculations are in good agreement with the experimental counterparts. The theoretical calculations correctly indicate that the F‒C‒C‒N dihedral angle in the synclinal form is about 67º, but underestimate the magnitude of the gauche effect and erroneously predict the antiperiplanar rotamer to be 1.3 – 1.6 kJ/mol more stable than the synclinal conformer.

• Samdal, Svein & Møllendal, Harald (2011). Microwave Spectrum and Conformational Composition of 1-Vinylimidazole. Journal of Physical Chemistry A. ISSN 1089-5639. 115(26), p. 7559–7565. doi: 10.1021/jp202319q. Full text in Research Archive Show summary

  The microwave spectrum of 1-vinylimidazole has been investigated in the 21 – 80 GHz spectral region. The spectra of two conformers have been assigned. One of these forms is planar, while the other is non-planar with the imdazole ring and the vinyl group forming an angle of 15(4)° from co-planarity. The planar form is found to be 5.7(7) kJ/mol more stable than the non-planar rotamer by relative intensity measurements. The spectra of 10 vibrationally excited states of the planar form and one excited-state spectrum of the non-planar form were assigned. The vibrational frequencies of several of these states were determined by relative intensity measurements. The microwave work has been augmented by quantum chemical calculations at the CCSD/cc-pVTZ, MP2/cc-pVTZ, and B3LYP/cc-pVTZ levels of theory. The B3LYP calculations predict erroneously that both forms of 1-vinylimidazole are planar, whereas the MP2 and CCSD calculations correctly predict the existence of a planar and a non-planar conformer of this compound.

• Shen, Q. & Samdal, Svein (2011). The molecular structures and conformational compositions of 1,3 cyclohexanedione and 1,4 cyclohexanedione as determined by gas-phase electron diffraction and theoretical calculation. Journal of Molecular Structure. ISSN 0022-2860. 1005(1-3), p. 156–160. doi: 10.1016/j.molstruc.2011.08.043. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Matrane, Abdellatif & Guillemin, Jean-Claude (2011). Synthesis, Microwave Spectrum, and Dipole Moment of Allenylisocyanide (H2C=C=CHNC), a Compound of Potential Astrochemical Interest. Journal of Physical Chemistry A. ISSN 1089-5639. 115(27), p. 7978–7983. doi: 10.1021/jp204296n. Full text in Research Archive Show summary

  An improved synthesis of a compound of potential astrochemical interest, allenylisocyanide (H2C=C=CHNC), is reported together with its microwave spectrum, which has been investigated in the 8 – 120 GHz spectral range to facilitate a potential identification in interstellar space. The spectra of the ground vibrational state and of five vibrationally excited states belonging to three different vibrational modes have been assigned for the parent species. A total of 658 transitions with a maximum value of J = 71 were assigned for the ground state and accurate values obtained for the rotational and quartic centrifugal distortion constants. The spectra of five heavy-atom (13C and 15N) isotopologues were also assigned. The dipole moment was determined to be a = 11.93(16), b = 4.393(44), and tot = 12.71(16) × 10‒30 C m. The spectroscopic work has been augmented by theoretical calculations at the CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory. The theoretical calculations are generally in good agreement with the experimental results.

• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2011). Microwave Spectrum, Conformational Composition, and Intramolecular Hydrogen Bonding of (2-Chloroethyl)amine (ClCH2CH2NH2). Journal of Physical Chemistry A. ISSN 1089-5639. 115(17), p. 4334–4341. doi: 10.1021/jp201263c. Full text in Research Archive Show summary

  The microwave spectrum of (2-chloroethyl)amine, ClCH2CH2NH2, has been investigated in the 22 – 120 GHz region. Five rotameric forms are possible for this compound. In two of these conformers, denoted I and II, the Cl−C−C−N chain of atoms is antiperiplanar, with different orientation of the amino group. The link of the said atoms is synclinal in the three remaining forms, III – V, which differ with respect to the orientation of the amino group. The microwave spectra of four of these conformers, I – IV, have been assigned. In two of these rotamers, III and IV, the amino group is oriented in such a manner that rare and weak five-membered N−H ••• Cl intramolecular hydrogen bonds are formed. The geometries of conformers I and II precludes a stabilization by this interaction. The energy differences between the conformers were obtained from relative intensity measurements of spectral lines. The hydrogen-bonded conformer IV represents the global energy minimum. This rotamer is 0.3(7) kJ/mol more stable than the other hydrogen-bonded conformer III, 4.1(11) kJ/mol more stable than II, and 5.5(15) kJ/mol more stable than I. The spectroscopic work has been augmented by quantum chemical calculations at the CCSD/cc-pVTZ and MP2/6-311++G(3df,3pd) levels of theory. The CCSD rotational constants and energy differences are in good agreement with their experimental counterparts.

• Hnyk, Drahomir; Wann, Derek A.; Holub, Josef; Samdal, Svein & Rankin, David W. H. (2011). Why is the antipodal effect in closo-1-SB9H9 so large? A possible explanation based on the geometry from the concerted use of gas electron diffraction and computational methods. Dalton Transactions. ISSN 1477-9226. 40(21), p. 5734–5737. doi: 10.1039/c1dt10053j. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein & Guillemin, Jean-Claude (2011). Microwave Spectrum and Conformational Composition of 2-Chloroethylisocyanide. Journal of Physical Chemistry A. ISSN 1089-5639. 115(46), p. 13474–13481. doi: 10.1021/jp208580m. Full text in Research Archive Show summary

  2-Chloroethylisocyanide, ClCH2CH2N≡C, has been synthesized and its microwave spectrum has been investigated in the 20–97 GHz spectral region. The spectra of 35Cl and 37Cl isotopologues of two conformers have been assigned. The Cl‒C‒C‒N chain of atoms is antiperiplanar in one of these rotamers and synclinal in the second. The energy difference between the two forms has been obtained from relative intensity measurements. It was found that the antiperiplanar conformer is favored over the synclinal form by 4.3(8) kJ/mol. Quantum chemical calculations at the CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory have been performed. Most, but not all, of the spectroscopic constants predicted in these calculations are in good agreement with their experimental counterparts. The theoretical calculations correctly predict the 2-chloroethylisocyanide exists as a mixture of an antiperiplanar and a synclinal conformer with the former about 3.5 kJ/mol more stable than the latter. Both methods of calculations finds that the antiperiplanar rotamer has a symmetry plane. The dihedral angle formed by the Cl‒C‒C‒N link of atoms of the synclinal form is 67º according to the CCSD calculations. It is estimated from a comparison with the experimental rotational constants that this dihedral angle is uncertain by ±3º.

• Samdal, Svein; Møllendal, Harald; Hnyk, Drahomir & Holub, Josef (2011). Microwave Spectra and Structures of 1,2-(ortho)- and 1,7-(meta)-Carborane, C2B10H12. Journal of Physical Chemistry A. ISSN 1089-5639. 115(15), p. 3380–3385. doi: 10.1021/jp200820d. Full text in Research Archive Show summary

  The microwave spectra of 1,2- and 1,7-dicarba-closo-dodecaborane(12), C2B10H12, (ortho- and meta-carborane) have been recorded for the first time at room temperature in the 32 – 88 and 24 – 80 GHz spectral ranges, respectively. The spectra of the parent species (1,2-C211B10H12 and 1,7-C211B10H12) have been assigned together with four mono-substituted (10B) 1,2-C210B11B9H12 and 1,7-C210B11B9H12 isotopologues. The microwave spectra confirm that the structures of each of these two molecules are slightly distorted icosahedrons of C2V symmetry. A previous determination of the gaseous structures of these two carboranes by the gas electron diffraction method was based on several assumptions about the B−B bond length differences. All B−B bond lengths have now been redetermined using the substitution (rs) method, which is independent of such restraints. While several of the rs and electron-diffraction bond lengths are in good agreement, there are also differences of up to 0.026 Å. Quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level of theory have also been performed.

• Hnyk, Drahomir; Samdal, Svein; Exner, Otto; Wann, DA & Rankin, David W. H. (2010). Does 2-Methylacetophenone Comply with Steric Inhibition of Resonance? A Direct Experimental Proof of Its Nonplanar Conformation from a Joint Ab Initio/Electron Diffraction Analysis. Journal of Organic Chemistry. ISSN 0022-3263. 75(15), p. 4939–4943. doi: 10.1021/jo100291r. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Guirgis, Gamil A. & Wurrey, C. J. (2010). Microwave and Quantum Chemical Study of Allyldifluorosilane (H2C=CHCH2SiF2H). Journal of Physical Chemistry A. ISSN 1089-5639. 114(24), p. 6608–6612. doi: 10.1021/jp101950z. Full text in Research Archive Show summary

  Abstract The microwave spectrum of allyldifluorosilane (H2C=CHCH2SiF2H) has been investigated for the first time in the 28 – 80 GHz spectral interval at a temperature of −30 °C. The spectrum of the ground vibrational state of one conformer characterized by an anticlinal orientation for the C=C−C−Si chain of atoms and a synclinal conformation for the C−C−Si−H link has been assigned. This rotamer was found to be at least 2 kJ/mol more stable than further rotameric forms. The spectroscopic investigation has been augmented with quantum chemical calculations employing the MP2 and B3LYP methods using the 6-311++G(3df,3pd) basis set. The theoretical predictions are generally in good agreement with the experimental results.

• Phillips, Leo; Cooper, Mervyn K.; Haaland, Arne; Samdal, Svein; Giricheva, N. I. & Girichev, Georgii V. (2010). The molecular structure, equilibrium conformation and barrier to internal rotation in decachloroferrocene, Fe(eta-C5Cl5)(2), determined by gas electron diffraction. Dalton Transactions. ISSN 1477-9226. 39(19), p. 4631–4635. doi: 10.1039/c001366h. Full text in Research Archive
• Samdal, Svein; Guillemin, Jean-Claude & Gundersen, Snefrid (2010). Molecular Structure of Trichloroethenylgermane, CH2=CH-GeCl3, as Studied by Gas-Phase Electron Diffraction. Experimental Determination of the Barrier of Internal Rotation of the Trichlorogermyl Group Supplemented with Quantum Chemical Calculations on CH2=CH-MX3 (M = C, Si, Ge, Sn, and X = H, Cl). Journal of Physical Chemistry A. ISSN 1089-5639. 114(21), p. 6331–6335. doi: 10.1021/jp101706z. Full text in Research Archive
• Thomassen, Hanne; Gundersen, Snefrid & Samdal, Svein (2009). The molecular structures, conformations and force fields of bis(chloroimino)butanedinitrile as studied by gas-phase electron diffraction and quantum chemical calculations. Journal of Molecular Structure. ISSN 0022-2860. 928(1-3), p. 182–188. doi: 10.1016/j.molstruc.2009.03.032. Full text in Research Archive
• Strand, Tor G; Gundersen, Snefrid; Priebe, Hanno; Samdal, Svein & Seip, Ragnhild (2009). Molecular structures, conformations, force fields and large amplitude motion of cis-3-chloro-2-propen-1-ol as studied by quantum chemical calculations and gas electron diffraction augmented with quantum chemical calculations on 2-propen-1-ol. Journal of Molecular Structure. ISSN 0022-2860. 921(1-3), p. 72–79. doi: 10.1016/j.molstruc.2008.12.036. Full text in Research Archive
• Shen, Q; Trætteberg, Marit & Samdal, S (2009). The molecular structure of gaseous 1,2 cyclohexanedione. Journal of Molecular Structure. ISSN 0022-2860. 923(1-3), p. 94–97. doi: 10.1016/j.molstruc.2009.02.006. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein & Volden, Hans Vidar (2008). Molecular structures of chloro(phthalocyaninato)-aluminum(III) and -gallium(III) as determined by gas electron diffraction and quantum chemical calculations: Quantum chemical calculations on fluoro(phthalocyaninato)-aluminum(III) and -gallium(III), chloro(tetrakis(1,2,5-thiadiazole)porphyrazinato)-aluminum(III) and -gallium(III) and comparison with their X-ray structures. Journal of Physical Chemistry A. ISSN 1089-5639. 112(38), p. 9075–9082. doi: 10.1021/jp804105d. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein & Volden, Hans Vidar (2008). Molecular Structure of Phthalocyaninatotin(II) Studied by Gas-Phase Electron Diffraction and High-Level Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 112(40), p. 10046–10052. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein & Volden, Hans Vidar (2008). Molecular structure of the trans and cis isomers of metal-free phthalocyanine studied by gas-phase electron diffraction and high-level quantum chemical calculations: NH tautomerization and calculated vibrational frequencies. Journal of Physical Chemistry A. ISSN 1089-5639. 112(21), p. 4853–4860. doi: 10.1021/jp801284c. Full text in Research Archive
• Gundersen, Snefrid; Samdal, Svein; Strand, Tor G & Volden, Hans Vidar (2007). Benzene; high level quantum chemical calculations, gas electron diffraction pattern recorded on Fuji imaging plates and a method to explore systematic discrepancies which was used to determine an improved sector correction. Journal of Molecular Structure. ISSN 0022-2860. 832, p. 164–171. doi: 10.1016/j.molstruc.2006.08.016. Full text in Research Archive
• Samdal, Svein; Volden, Hans Vidar; Ferro, V. R.; Vega, J. M. Garcia de la; Gonzales-Rodriguez, D. & Torres, T. (2007). Molecular Structure of Chloro-dodecafluorosubphthalocyanato Boron(III) by Gas-Phase Electron Diffraction and Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 111, p. 4542–4550. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein & Volden, Hans Vidar (2007). Molecular Structures of Phthalocyaninatozinc and Hexadecafluorophthalocyaninatozinc Studied by Gas-Phase Electron Diffraction and Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 111, p. 12011–12018. doi: 10.1021/jp074455n. Full text in Research Archive
• Naumov, V. A.; Naumov, A. V. & Samdal, Svein (2007). Molecular structure of diphenylchlorophosphine in the gas phase. Russian journal of general chemistry. ISSN 1070-3632. 77(4), p. 553–560. doi: 10.1134/S1070363207040081. Full text in Research Archive
• Girichev, Georgii V.; Giricheva, N. I.; Haaland, Arne; Kuzmina, NP; Samdal, Svein & Strenalyuk, Tatyana [Show all 8 contributors for this article] (2006). Molecular structures of tris(dipivaloylmethanato) complexes of the lanthanide metals, Ln(dpm)(3), studied by gas electron diffraction and density functional theory calculations: A comparison of the Ln-O bond distances and enthalpies in Ln(dpm)(3) complexes and the cubic sesquioxides, Ln(2)O(3). Inorganic Chemistry. ISSN 0020-1669. 45, p. 5179–5186. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2006). Molecular Structure of Propargylgermane (2-Propynylgerman) Determined by Gas-Phase Electron Diffraction and Quantum Chemical Calculations. Journal of Molecular Structure. ISSN 0022-2860. 780-781, p. 157–162. Full text in Research Archive Show summary

  The molecular structure of propargylgermane, HCCCH2GeH3, has been determined by gas-phase electron diffraction. The electron-diffraction investigation has been supported by density functional theory and ab initio calculations. The ra value of the bond lengths (pm) are: r(C-Ge) = 197.2(1); r(C-C) = 143.9(2); r(CC) = (123.1(1); r(H-Cacetylene) = 108.5(3); r(C-H) = 111.6(3) and r(Ge-Haverage) = 153.8(2). The Ge-C-C angle is 111.7(1) and the C-CC angle is 178.3(4). The uncertainties are one standard deviation from the least-squares refinement.

• Strenalyuk, Tatyana; Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2006). Structures of Vinylstannane (Ethynylstannane) and Allystannane (2-Propenylstannane) Determined by Gas-Phase Electron Diffraction and Quantum Chemical Calculations. Organometallics. ISSN 0276-7333. 25, p. 2626–2633. Full text in Research Archive
• Strenalyuk, Tatyana; Samdal, Svein; Møllendal, Harald & Guillemin, Jean-Claude (2006). Structures of 1,2-Propadienylgermane (Allenylgermane) and 1,2-Propadienylstannane (Allenylstannane) Determined by Gas-Phase Electron Diffraction and Quantum Chemical Calculations. Organometallics. ISSN 0276-7333. 25, p. 2090–2096. Full text in Research Archive
• Møllendal, Harald & Samdal, Svein (2006). Conformation and Intramolecular Hydrogen Bonding of 2-Chloroacetamide as Studied by Microwave Spectroscopy and Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 110, p. 2139–2146. Full text in Research Archive Show summary

  Abstract The microwave spectrum of 2-chloroacetamide (ClCH2CONH2) has been investigated at room temperature in the 19 – 80 GHz spectral range. Spectra of the 35ClCH2CONH2 and 37ClCH2CONH2 isotopomers of one conformer, which has a symmetry plane (Cs symmetry), were assigned. The amide group is planar and an intramolecular hydrogen bond is formed between the chlorine atom and the nearest hydrogen atom of the amide group. The ground vibrational state, six vibrationally excited states of the torsional vibration about the CC bond as well as the first excited state of the lowest bending mode were assigned for the 35ClCH2CONH2 isotopomer, whereas the ground vibrational state of 37ClCH2CONH2 was assigned. The CC torsional fundamental vibration has a frequency of 62(10) cm-1 and the bending vibration has a frequency of 204(30) cm-1. The rotational constants of the ground and of the six excited states of the CC torsion were fitted to the potential function V(z) = 16.1(<z4> + 2.3<z2>) cm-1, where z is a dimensionless parameter. This function indicates that the equilibrium conformation has Cs symmetry. Rough values of the chlorine nuclear quadrupole coupling constants were derived as Xaa = -47.62(52) and Xbb = 8.22(66) MHz for the 35Cl nucleus and Xaa = -34.6(10) and Xbb = 6.2(11) MHz for the 37Cl nucleus. Ab initio and density functional theory quantum chemical calculations have been performed at several levels of theory to evaluate the equilibrium geometry of this compound. The density functional theory calculations at the B3LYP/6-311++G(3df,2pd) and B3LYP/cc-pVTZ levels of theory as well as ab initio calculations at the MP2(F)/cc-pVTZ level predict correct lowest-energy conformation for the molecule, whereas the ab initio calculations at the QCISD(FC)/6-311G(d) and MP2(F)/6-311++G(d,p) levels predict an incorrect equilibrium conformation.

• Atavin, E. G.; Khristenko, L.V.; Lokshin, Boris V.; Samdal, Svein; Kirpichenko, S. V. & Vilkov, L. V. (2005). GAS-PHASE ELECTRON DIFFRACTION, VIBRATIONAL SPECTROSCOPY, AND QUANTUM CHEMICAL STUDIES OF THE MOLECULAR STRUCTURE OF 3,3-DIMETHYL-3-SILATHIANE. Journal of Structural Chemistry. ISSN 0022-4766. 46(3), p. 422–430. Full text in Research Archive
• Naumov, V. A.; Tafipolskii, M. A.; Naumov, A. V. & Samdal, Svein (2005). Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry. Russian journal of general chemistry. ISSN 1070-3632. 75(6), p. 923–932. Full text in Research Archive
• Horn, Anne; Klæboe, Peter; Nielsen, Claus Jørgen; Samdal, Svein & Guirgis, Gamil A. (2005). Conformational equilibrium of Ethoxytrichlorosilane investigated by infrared and Raman spectroscopy and by ab initio calculations. Bulgarian Chemical Communications. ISSN 0861-9808. 37(4), p. 332–343. Full text in Research Archive
• Naumov, V. A.; Samdal, Svein; Naumov, A. V.; Gundersen, Snefrid & Volden, Hans Vidar (2005). Molecular Structure of Triphenylamine in the Gas Phase. Russian journal of general chemistry. ISSN 1070-3632. 75(12), p. 1956–1961. Full text in Research Archive
• Gundersen, Snefrid; Samdal, Svein; Seip, Ragnhild & Strand, Tor G (2004). The molecular structure, conformation, force field and potential function to internal rotation of 2,2-dichloroacetamide as studied by quantum chemical calculations and gas electron diffraction data from photographic plates using a commercial scanner. Journal of Molecular Structure. ISSN 0022-2860. 691, p. 149–158. Full text in Research Archive
• Shishkov, IF; Khristenko, LV; Rudakov, FM; Golubinskii, AB; Vilkov, LV & Karlov, SS [Show all 8 contributors for this article] (2004). Molecular structure of silatrane determined by gas electron diffraction and quantum-mechanical calculations. Structural Chemistry. ISSN 1040-0400. 15, p. 11–16. Full text in Research Archive
• Novikov, V. P.; Samdal, Svein & Vilkov, L. V. (2004). Molecular structure and conformation of N,N-dimethylaniline by gas-phase electron diffraction and quantum-chemical calculations. Russian journal of general chemistry. ISSN 1070-3632. 74(8), p. 1247–1253. Full text in Research Archive
• Novikov, V. P.; Samdal, Svein & Vilkov, L. V. (2004). Molecular structure and Internal Rotation Potential of Dimethylphenylphosphine, According to Gas-Phase Electron Diffraction Data and Quantum-Chemical Calculations. Russian journal of general chemistry. ISSN 1070-3632. 74(7), p. 1072–1079. Full text in Research Archive
• Shishkov, IF; Khristenko, LV; Samdal, Svein; Gundersen, Snefrid; Volden, Hans Vidar & Vilkov, LV (2004). Electron diffraction study of meta- and para-fluoronitrobenzene using results from quantum chemical calculations. Trends in the carbon-halogen bond length found in ortho-, meta- and para-halonitrobenzenes (Halo = F, Cl, Br, I). Journal of Molecular Structure. ISSN 0022-2860. 693, p. 133–140. Full text in Research Archive
• Samdal, Svein; Hedberg, Lise; Hedberg, Kenneth; Richardson, Alan D.; Bancu, Mihail & Scott, Lawrence T. (2003). Gas-Phase Molecular Structure of Decachlorocorannulene, C20Cl10. An Electron-Diffraction Study Augmented by ab initio, DFT and Normal Coordinate Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 107(3), p. 411–417. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Holub, Josef & Hnyk, Drahomir (2003). The Structure of 1-Thia-closo-dodecaborane(11), 1-SB11H11, as Determined by Microwave Spectroscopy Complemented by Quantum Chemical Calculations. Inorganic Chemistry. ISSN 0020-1669. 42, p. 3043–3046. Full text in Research Archive Show summary

  The microwave spectrum of 1-thia-closo-dodecaborane(11), 1-SB11H11, has been investigated in the 23 - 62 GHz spectral region. The molecule is found to have C5v symmetry. The spectra of several isotopomers have been assigned and a precise substitution structure of the non-hydrogen atoms has been determined. The structure is in quite good agreement with the one determined previously by electron diffraction. Density functional theory calculations at the B3LYP/cc-pVTZ level were found to predict a structure that is in good agreement with the substitution structure.

• Samdal, Svein & Møllendal, Harald (2003). The Structural and Conformational Properties of Formic Hydrazide (Formylhydrazine) Studied by Microwave Spectroscopy and Quantum Chemical Calculations. Journal of Physical Chemistry A. ISSN 1089-5639. 107, p. 8845–8850. Full text in Research Archive Show summary

  Formic hydrazide (formylhydrazine) has been investigated by microwave spectroscopy in the 8 - 62 GHz spectral range, as well as by quantum chemical ab initio and density functional theory calculations made at several levels of theory. Both the ab initio and the density functional theory calculations predict that two stable forms exist for this compound, a more stable conformer having a syn-periplanar arrangement for the heavy atoms, and a less stable form where these atoms are anti-periplanar. The latter rotamer is calculated to be 10-14 kJ/mol less stable than the former depending on the theoretical approach. The barrier height separating the two forms is calculated to be 92.2 kJ/mol at the B3LYP/cc-pVTZ level. The microwave spectra of the ground and four vibrationally excited states of the lowest torsional mode of the syn-periplanar conformer were assigned. The lowest torsional frequency was determined to be 77(15) cm-1 by relative intensity measurements. The variation of the rotational constants upon excitation of this mode and the lowest torsional frequency were fitted to a potential function of the form V(z) = 15.6(<z4> + 4.9<z2>) cm-1, indicating that the heavy atoms are effectively planar at the equilibrium conformation. The dipole moment was determined to be &#956;a = 1.54(2), &#956;b = 1.85(2), &#956;c = 0 (assumed) and &#956;tot = 2.41(3) D [8.04(8) × 10-30 C m] by Stark effect measurements.

• Shishkov, Igor F.; Khristenko, Lyudmila V.; Vilkov, Lev V.; Samdal, Svein & Gundersen, Snefrid (2003). Molecular Structure of ortho-Fluoronitrobenzene Studied by Gas Electron Diffraction and Ab Initio MO Calculations. Structural Chemistry. ISSN 1040-0400. 14(2), p. 151–157. Full text in Research Archive
• Haaland, Arne; Samdal, Svein; Tverdova, Natalya V.; Girichev, Georgii V.; Girichev, Nina I. & Shlykov, Sergej A. [Show all 8 contributors for this article] (2003). The molecular structure of dicyclopentadienylzinc (zincocene) determined by gas electron diffraction and density functional theory calculations: eta-5, eta-5, eta-3, eta-3, or eta-5, eta-1 coordination of the ligand rings? Journal of Organometallic Chemistry. ISSN 0022-328X. 684, p. 351–358. Full text in Research Archive
• Samdal, S.; Richardson, Alan D.; Hedberg, Kenneth; Gadgil, V. R.; Meyer, M. M. & Williams, R. V. (2003). Gas-phase electron-diffraction investigation and quantum chemical calculations of the structure of 1,5-dimethyl-2,4,6,8-semibullvalenetetracarboxylic dianhydride. Helvetica Chimica Acta. ISSN 0018-019X. 86, p. 1741–1752. Full text in Research Archive
• Naumov, V. A.; Tafipolskii, M. A. & Samdal, Svein (2003). Molecular structure of phenylphosphine and its analogs by gas-phase electron diffraction and quantum chemical calculations. Russian journal of general chemistry. ISSN 1070-3632. 73, p. 896–902. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Holub, Josef & Hnyk, Drahomir (2002). The Structure of 1-Thia-closo-decaborane(9), 1-SB9H9, as Determined by Microwave Spectroscopy and Quantum Chemical Calculations. Inorganic Chemistry. ISSN 0020-1669. 41, p. 4574–4578. Full text in Research Archive Show summary

  The microwave spectrum of 1-thia-closo-decaborane(9), 1-SB9H9, has been investigated in the 12 - 61 GHz spectral region. The molecule has C4v symmetry. The spectra of five isotopomers have been assigned and a precise substitution structure of the non-hydrogen atoms has been determined. It was found that the axial sulfur atom causes a substantial expansion of the B4 belt adjacent to sulfur and hence to a significant distortion from a regular bicapped square antiprismatic structure. The experimental work has been supplemented by high-level ab initio (MP2/6-311G**) and density functional theory calculations (B3LYP/6-311G** and B3LYP/cc-pVTZ). The agreement between the substitution structure and the two DFT calculations is very good in each case. The agreement is considerably poorer for the MP2/6-311G** calculations, particularly for the sulfur-boron bond length.

• Naumov, V. A.; Tafipolskii, M. A.; Naumov, A. V. & Samdal, Svein (2002). Molecular Structure of diphenylphosphine as determined by gas-phase electron diffraction and quantum chemical calculations. Russian journal of general chemistry. ISSN 1070-3632. 72, p. 1894–1900. Full text in Research Archive
• Shishkov, Igor F.; Khristenko, Lyudmila V.; Rudakov, F.M.; Vilkov, Lev V.; Karlov, S.S. & Zaitseva, G.S. [Show all 7 contributors for this article] (2002). The molecular structure of boratrane determined by gas electron diffraction and quantum mechanical calculations. Journal of Molecular Structure. ISSN 0022-2860. 641(2-3), p. 199–205. Full text in Research Archive
• Marstokk, Karl-Magnus; Møllendal, Harald; Samdal, Svein & Steinborn, D. (2001). Microwave spectrum, molecular structure, conformational equilibrium, vibrational frequencies and quantum chemical calculations for methyl vinyl sulfide. Journal of Molecular Structure. ISSN 0022-2860. 567-568, p. 41–57. Full text in Research Archive Show summary

  This paper reports the microwave spectra of the syn and skew conformers of methyl vinyl sulfide.

• Naumov, V. A.; Tafipolskii, M. A.; Naumov, A. V.; Shorokhov, D. Yu. & Samdal, Svein (2001). Molecular structure of triphenylphosphine by gas-phase electron diffraction and ab initio calculations. Russian journal of general chemistry. ISSN 1070-3632. 71(8), p. 1225–1232. Full text in Research Archive
• Hnyk, Drahomir; Borisenko, Konstantin B.; Samdal, Svein & Exner, Otto (2000). Structure of Methyl 2-Methylbenzoate: Steric Effect of a Small ortho-Substituent. European Journal of Organic Chemistry. ISSN 1434-193X. p. 2063–2069. Full text in Research Archive
• Marstokk, Karl-Magnus; Møllendal, Harald & Samdal, Svein (2000). Microwave Spectrum, Conformational Equilibrium, 14Nuclear Quadrupole Coupling Constants, Dipole Moment, Vibrational Frequencies and Quantum Chemical Calculations for Acrylamide. Journal of Molecular Structure. ISSN 0022-2860. 524, p. 69–85. Full text in Research Archive Show summary

  The microwave spectrum of acrylamide has been investigated in the 20.0-60.5 GHz spectral region at room temperature. Two conformers were assigned. The most stable rotamer is planar with the carbonyl and the vinyl groups in the syn position. The second less stable skew conformer is non-planar with the C=C-C=O chain of atoms approximately 155 degrees from syn. The syn form was found to be 6.5 kJ/mol more stable than skew.

• Novikov, V. P.; Tarasenko, S. A.; Samdal, Svein & Vilkov, L. V. (2000). The molecular structure and the puckering potential function of octamethylcyclotetrasilane, Si4Me8, determined by gas electron diffraction and relaxation constraints from ab initio calculations. Structural Chemistry. ISSN 1040-0400. 11, p. 111–119. Full text in Research Archive
• Novikov, Vladimir P.; Tarasenko, Svetlana A.; Samdal, Svein & Vilkov, Lev V. (2000). Electron diffraction study of molecular structure and inversion potential for 1,1-dimethylsilacyclobutane and 1,1,3,3-tetramethyl-1,3-disilacyclobutane. Journal of Structural Chemistry. ISSN 0022-4766. 41(2), p. 217–230. Full text in Research Archive
• Novikov, Vladimir P.; Tarasenko, Svetlana A.; Samdal, Svein & Vilkov, Lev V. (1999). The molecular structure and the puckering potential function of octamethylcyclotetrasilane, Si4Me8, determined by gas electron diffraction and ab initio calculations. Mendeleev communications (Print). ISSN 0959-9436. p. 217–219. Full text in Research Archive
• Samdal, Svein; Kochikov, I. V.; Tarasov, Yu. I.; Spirodonov, V. P.; Kuramshima, G. M. & Yagola, A. G. [Show all 8 contributors for this article] (1999). Extension of regularizing algorithm for determination of equilibrium geometry and force field of free molecules from joint use of electron diffraction, molecular spectroscopy and ab initio data on systems with large-amplitude oscillary motion. Journal of Molecular Structure. ISSN 0022-2860. 485-486, p. 421–443. Full text in Research Archive
• Samdal, Svein; Gundersen, Snefrid; Seip, Ragnhild & Shorokhov, Dimitry J. (1999). The molecular structure, conformation, potential to internal rotation and force field of 2,2-difluoroacetamide as studied by gas electron diffraction and quantum chemical calculations. Journal of Molecular Structure. ISSN 0022-2860. 477, p. 225–240. Full text in Research Archive
• Shishkov, Igor F.; Khristenko, Lyudmila V.; Sipachev, Victor A.; Vilkov, Lev V.; Samdal, Svein & Gundersen, Snefrid [Show all 7 contributors for this article] (1999). A reinvestigation of the molecular structure of dimethyl-N-nitramine by gas electron diffractio, ab initio calculations of the molecular geometry and the force field and vibrational spectra. Journal of Molecular Structure. ISSN 0022-2860. 485-486, p. 153–161. Full text in Research Archive
• Samdal, Svein; Novikov, Vladimir P.; Tarasenko, Svetlana A.; Shen, Quang & Vilkov, Lev V. (1999). The molecular structure and puckering potential function of 1,1,3,3-tetramethyl-1,3-disilacyclobutane determined by gas electron diffraction and relaxation constraints from ab initio calculations. Journal of Molecular Structure. ISSN 0022-2860. 485-486, p. 135–152. Full text in Research Archive
• Samdal, Svein; Novikov, Vladimir P.; Tarasenko, Svetlana A.; Shen, Quang & Vilkov, Lev V. (1999). The molecular structure and the puckering potential function of 1,1-dimethylsilacyclobutane determined by gas electron diffraction and relaxation constraints from ab initio calculations. Journal of Molecular Structure. ISSN 0022-2860. p. 71–89. Full text in Research Archive
• Samdal, Svein; Gundersen, Snefrid; Novikov, Vladimir P.; Seip, Ragnhild; Shorokhov, Dimitry J. & Sipachev, Victor A. (1999). The molecular structure, conformation, potential to internal rotation and force field of 2-chloro-2,2-difluoroacetamide applying gas electron diffraction, quantum chemical calculations and two different methods of vibrational corretions. Journal of Molecular Structure. ISSN 0022-2860. 485-486, p. 97–114. Full text in Research Archive
• Gundersen, Snefrid; Samdal, Svein; Seip, Ragnhild; Shorokhov, Dimitry J. & Strand, Tor G (1998). The molecular structure, conformation, potential to internal rotation and force field of 2,2,2-trichloroacetamide as studied by gas electron diffraction and quantum chemical calculations. Journal of Molecular Structure. ISSN 0022-2860. 445, p. 229–242. Full text in Research Archive
• Samdal, Svein; Borisenko, Konstantin B.; Suslova, Elena N.; Sipachev, Victor A.; Shishkov, Igor F. & Vilkov, Lev V. (1998). Molecular structure and pseudorotation in 3,3-dimethyl-3-silatetrahydro- thiophene from a joint gas-phase electron diffraction and ab initio molecular orbital study. Acta Chemica Scandinavica. ISSN 0904-213X. 52, p. 975–984. Full text in Research Archive
• Borisenko, Konstantin B.; Samdal, Svein; Shishkov, Igor F. & Vilkov, Lev V. (1998). Molecular structure and conformations of tetrahydrofurfuryl alcohol from a joint gas-phase electron diffraction and ab initio molecular orbital investigation. Journal of Molecular Structure. ISSN 0022-2860. 448, p. 29–41. Full text in Research Archive
• Samdal, Svein & Mastryukov, Vladimir S. (1998). Asymmetry in methyl group of ethane during internal rotation: Ab initio study. Journal of Computational Chemistry. ISSN 0192-8651. 19(10), p. 1141–1145. Full text in Research Archive
• Samdal, Svein (1998). Acetamide, a challenge to theory and experiment? On the molecular structure, conformation, potential to internal rotation of the methyl group and force fields of free acetamide as studied by quantum chemical calculations. Journal of Molecular Structure. ISSN 0022-2860. 440, p. 165–174. Full text in Research Archive
• Borisenko, K. B.; Samdal, Svein; Shishkov, I. F. & Vilkov, L. V. (1998). Intramolecular motion and molecular structure of N-nitropyrrolidine: A gas-phase electron diffraction and ab initio molecular orbital study. Acta Chemica Scandinavica. ISSN 0904-213X. 52, p. 312–321. Full text in Research Archive
• Novikov, V. P.; Tarasenko, S. A.; Samdal, Svein & Vilkov, L. V. (1998). The molecular structure and the puckering potential function of 1,1-dichloro-silacyclobutane determined by gas electron diffraction and relaxation constraints from ab initio calculations. Journal of Molecular Structure. ISSN 0022-2860. 445, p. 207–227. Full text in Research Archive
• Samdal, Svein & Seip, R. (1997). The molecular structure, conformation, potential to internal rotation and force field of 2,2,2-trichloroacetamide as studied by gas electron diffraction and ab initio calculations. Journal of Molecular Structure. ISSN 0022-2860. 413-414, p. 423–439. Full text in Research Archive
• Samdal, Svein; Strand, T. G.; Tafipolskii, M. A.; Vilkov, L. V.; Popik, M. V. & Volden, Hans Vidar (1997). The molecular structure of benzene derivatives. Part 1. 4-Fluorobenzaldehyde by joint analysis of gas electron diffraction, microwave spectroscopy and ab initio molecular orbital calculations. Journal of Molecular Structure. ISSN 0022-2860. 435, p. 89–99. Full text in Research Archive
• Novikov, V. P.; Samdal, Svein & Vilkov, L. V. (1997). Determination of the molecular structure and the internal rotation potential of dichlorophenylphosphine using gas electron diffraction and relaxation constraints from ab initio calculations. Journal of Molecular Structure. ISSN 0022-2860. 413-414, p. 279–292. Full text in Research Archive

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• Kveseth, Kari; Haaland, Arne & Samdal, Svein (2018). Artikkelserie om Elektrondiffraksjon i Norge 2. artikkel; Otto Chr. Bastiansen, Vitenskapelige høydepunkter. Kjemi. ISSN 0023-1983. 3, p. 18–25. Full text in Research Archive
• Møllendal, Harald & Samdal, Svein (2006). Conformation and Intramolecular Hydrogen Bonding of 2-Chloroacetamide as Studied by Microwave Spectroscopy and Quantum Chemical Calculations. Full text in Research Archive
• Gundersen, Snefrid; Samdal, Svein; Strenalyuk, Tatyana & Volden, Hans Vidar (2005). The molecular structure of phthalocyaninato- and hexadecafluoro phthalocyaninato-zinc and aluminum- and gallium-phthalocyanine chloride determined by gas-phase electron diffraction and DFT calculations. Full text in Research Archive
• Guillemin, Jean-Claude; Gundersen, Snefrid; Samdal, Svein; Strenalyuk, Tatyana & Volden, Hans Vidar (2005). The molecular structure of propargylgermane, allylstannane and vinylstannane studied by gas-phase electron diffraction and quantum chemical computations. Full text in Research Archive
• Møllendal, Harald; Samdal, Svein; Holub, Josef & Hnyk, Drahomir (2003). Microwave Spectrum and Structure of 1-Thia-closo-dodecaborane(11), 1-SB11H11. Full text in Research Archive Show summary

  The MW spectrum of this C5V symmetrical top has been assigned and an accurate structure has been determined. See Inorg. Chem. 42 (2003) 3043.

• Møllendal, Harald; Samdal, Svein; Holub, Josef & Hnyk, Drahomir (2002). The Structure of 1-Thia-closo-decaborane(9), 1-SB9H9, as Determined by Microwave Spectroscopy and Quantum Chemical Calculations. Full text in Research Archive Show summary

  The microwave spectrum of 1-thia-closo-decaborane(9), 1-SB9H9, has been investigated in the 12 - 61 GHz spectral region. The molecule has C4v symmetry. The spectra of five isotopomers have been assigned and a precise substitution structure of the non-hydrogen atoms has been determined. It was found that the axial sulfur atom causes a substantial expansion of the B4 belt adjacent to sulfur and hence to a significant distortion from a regular bicapped square antiprismatic structure. The experimental work has been supplemented by high-level ab initio (MP2/6-311G**) and density functional theory calculations (B3LYP/6-311G** and B3LYP/cc-pVTZ). The agreement between the substitution structure and the two DFT calculations is very good in each case. The agreement is considerably poorer for the MP2/6-311G** calculations, particularly for the sulfur-boron bond length.

• Zatula, Alexey; Uggerud, Einar; Helgaker, Trygve & Samdal, Svein (2012). Experimental and computational studies of dynamic processes in ionic water clusters. Universitetet i Oslo. Full text in Research Archive Show summary

  Clusters of water molecules mimic the transition from gas phase to bulk water. Cluster species of the desired sizes can be selected using mass spectrometric techniques and their size-dependent properties can thereby be measured. The properties of small ionic clusters are of particular relevance to atmospheric science, providing insights into nucleation phenomena. This work is dedicated to the investigation of properties of selected ionic molecular clusters and their gas phase reactions with heavy water or ammonia, with a strong emphasis on proton transfer phenomena. This has been achieved both experimentally in cluster beam experiments and by quantum chemical calculations. Both in the abundance spectra and the evaporation patterns of the investigated aqueous clusters “magic numbers” discontinuities in otherwise smoothly varying distributions were observed, and are discussed. To further examine a marked difference in the observed “magic-number” behaviour of H+(pyridine)1(H2O)n and H+(NH3)1(pyridine)1(H2O)n clusters, quantum chemical calculations have been employed. Next, relative reaction cross sections were measured for cluster ions reacting with D2O and with NH3 in the collision cell. Analysis of the results for the reaction H+(pyridine)1(H2O)n + NH3 allowed us to improve a kinetic model of the atmospheric positive ion composition. Upon reaction of a cluster with D2O a short-lived reaction intermediate is formed, which is followed by subsequent loss of D2O, HDO or H2O. The reaction channel leading to the loss of HDO requires proton mobility within the cluster, involving O–H-bond activation. The loss of HDO was not observed for protonated water clusters containing one pyridine molecule, a consequence of the immobilizing effect on the extra proton by the nitrogen base site. Similarly, the rates of protium/deuterium exchange for water clusters containing alkali metal ions are consistently extremely low. However, the experiments show enhanced proton mobility in water clusters containing two or three pyridine molecules (H+(pyridine)2–3(H2O)n), in 2,2'-bipyridine and 2,2'-ethylenebipyridine containing water clusters as well as in bisulfate water clusters (HSO4?(H2O)n). On the basis of systematic quantum chemical calculations we present consistent mechanisms for low energy water rearrangement and proton transfer along preformed "wires" of hydrogen bonds between the two distinct sites provided by these core ions in complete support of the experimental findings.

• Strenalyuk, Tatyana; Samdal, Svein & Helgaker, Trygve (2008). Molecular structure of phthalocyanine complexes using gas-phase electron diffraction and quantum chemical calculations. Universitetet i Oslo. Full text in Research Archive
• Gundersen, Grete; Haaland, Arne; Samdal, Svein; Strand, Tor G; Hagen, Kolbjørn & Stølevik, Reidar [Show all 7 contributors for this article] (1999). THE NORWEGIAN ELECTRON DIFFRACTION GROUP Annual report 1998. Departments of chemistry, Univerity of Oslo and the Norwegian University of Science and Technology, Trondheim. Full text in Research Archive Show summary

  CONTENTS 1. Personnel and Co-Workers. page 3. 1.1 The Norwegian Electron Diffraction Group. page 3. 1.2. Co-workers. page 5. 2. Experimental and computations. page 9. 3. Inorganic and Organometallic Compounds. page 19. 4. Organic Compounds. page 34. 5. List of Publications. page 48. References to the 27 articles by members of the group printed in 1998 are listed.

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