Claus Jørgen Nielsen

• Bunkan, Arne Joakim C.; Gorzkowska-Sobas, Agnieszka A; Brinchmann, Erika Zardin; Languille, Baptiste; Mikoviny, Tomas & Nielsen, Claus Jørgen [Vis alle 8 forfattere av denne artikkelen] (2026). Characterization of a Pilot-Scale Corona Radical Shower Non-Thermal Plasma Discharge Using Propene. Plasma chemistry and plasma processing. ISSN 0272-4324. 46(3). doi: 10.1007/s11090-026-10646-8. Fulltekst i vitenarkiv Vis sammendrag

  A pilot-scale non-thermal plasma unit (NTP) and a UV-C photolysis unit for industrial emission control were integrated in the wind tunnel facility at the Norwegian Defence Research Establishment and characterized employing propene as model VOC. The experiments were monitored by high-resolution Proton-Transfer-Reaction Time-of-Flight mass spectrometry (PTR-ToF-MS), and the results show that gas phase chemistry in the NTP discharge strongly resembles the naturally occurring OH radical-induced oxidation in the Earth’s atmosphere – the main products being formaldehyde, acetaldehyde, acetone, and hydroxy acetone. A chemical box model, based on a well-established atmospheric oxidation mechanism, reproduces the experimental results and allows identification of chemical ‘hot-spots’ in the system.

• Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & Zhu, Liang (2024). Experimental and Theoretical Study of the OH-Initiated Degradation of Ethylenediamine (NH<inf>2</inf>CH<inf>2</inf>CH<inf>2</inf>NH<inf>2</inf>) under Simulated Atmospheric Conditions. Part 1: Kinetics of the Ethylenediamine + OH Gas Phase Reaction. ACS Earth and Space Chemistry. doi: 10.1021/acsearthspacechem.4c00271. Fulltekst i vitenarkiv Vis sammendrag

  The ethylenediamine (NH2CH2CH2NH2) reaction with OH radicals was studied under natural sunlight conditions in a large outdoor atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ quantum chemistry results. The OH rate coefficient was determined in relative rate experiments employing online PTR-ToF-MS detection to be kOH = (2.8 ± 0.8) × 10–10 cm3 molecule–1 s–1 at 308 ± 3 K and 1013 ± 3 hPa. The theoretical study includes a conformational mapping of ethylenediamine showing nine conformers to be considered in reaction kinetics modeling, CCSD(T*)-F12a/aug-cc-pVTZ optimized geometries, and results from vibrational anharmonicity calculations for all conformers. The rate coefficients for the OH radical reaction with each of the nine ethylenediamine conformers were obtained in master equation calculations showing the kinetics being governed by both the formation of prereaction adducts and by tight transition states giving a Boltzmann conformer weighted rate coefficient kOH = 2.9 × 10–10 cm3 molecule–1 s–1, and a 1:1 branching between H-abstraction from the NH2 and CH2 groups at 298 K and 1013 hPa. The calculated rate coefficient shows a negative temperature dependence and a negligible variation with pressure under atmospheric conditions. The theoretical kinetics data were aligned to the experimental result, and the rate coefficient in the 200–400 K region can be approximated by a modified Arrhenius expression k(T) = 1.23 × 10–10 × (T/298)0.6 × exp(249 K/T) cm3 molecule–1 s–1.

• Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & D'Anna, Barbara [Vis alle 13 forfattere av denne artikkelen] (2024). Experimental and Theoretical Study of the OH-Initiated Degradation of Piperidine under Simulated Atmospheric Conditions. Journal of Physical Chemistry A. ISSN 1089-5639. 128(14), s. 2789–2814. doi: 10.1021/acs.jpca.3c08415. Fulltekst i vitenarkiv Vis sammendrag

  The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be kOH-piperidine = (1.19 ± 0.27) × 10–10 cm3 molecule–1 s–1 at 304 ± 2 K and 1014 ± 2 hPa. Product studies show the piperidine + OH reaction to proceed via H-abstraction from both CH2 and NH groups, resulting in the formation of the corresponding imine (2,3,4,5-tetrahydropyridine) as the major product and in the nitramine (1-nitropiperidine) and nitrosamine (1-nitrosopiperidine) as minor products. Analysis of 1-nitrosopiperidine photolysis experiments under natural sunlight conditions gave the relative rates jrel = j1-nitrosoperidine/jNO2 = 0.342 ± 0.007, k3/k4a = 0.53 ± 0.05 and k2/k4a = (7.66 ± 0.18) × 10–8 that were subsequently employed in modeling the piperidine photo-oxidation experiments, from which the initial branchings between H-abstraction from the NH and CH2 groups, kN–H/ktot = 0.38 ± 0.08 and kC2–H/ktot = 0.49 ± 0.19, were derived. All photo-oxidation experiments were accompanied by particle formation that was initiated by the acid–base reaction of piperidine with nitric acid. Primary photo-oxidation products including both 1-nitrosopiperidine and 1-nitropiperidine were detected in the particles formed. Quantum chemistry calculations on the OH initiated atmospheric photo-oxidation of piperidine suggest the branching in the initial H-abstraction routes to be ∼35% N1, ∼50% C2, ∼13% C3, and ∼2% C4. The theoretical study produced an atmospheric photo-oxidation mechanism, according to which H-abstraction from the C2 position predominantly leads to 2,3,4,5-tetrahydropyridine and H-abstraction from the C3 position results in ring opening followed by a complex autoxidation, of which the first few steps are mapped in detail. H-abstraction from the C4 position is shown to result mainly in the formation of piperidin-4-one and 2,3,4,5-tetrahydropyridin-4-ol, whereas H-abstraction from N1 under atmospheric conditions primarily leads to 2,3,4,5-tetrahydropyridine and in minor amounts of 1-nitrosopiperidine and 1-nitropiperidine. The calculated rate coefficient for the piperidine + OH reaction agrees with the experimental value within 35%, and aligning the theoretical numbers to the experimental value results in k(T) = 2.46 × 10–12 × exp(486 K/T) cm3 molecule–1 s–1 (200–400 K).

• Nielsen, Claus Jørgen & Tang, Yizhen (2023). Comment on “Theoretical study of the NO3 radical reaction with CH2ClBr, CH2ICl, CH2BrI, CHCl2Br, and CHClBr2” by I. Alkorta, J. M. C. Plane, J. Elguero, J. Z. Dávalos, A. U. Acuña and A. Saiz-Lopez, Phys. Chem. Chem. Phys. 2022, 24, 14365. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 25(5), s. 4355–4356. doi: 10.1039/d2cp03013f. Fulltekst i vitenarkiv Vis sammendrag

  This comment addresses a systematic error in the potential energy surfaces of the title reactions presented in the original article by Alkorta et al. The NO3 radical has D3h symmetry in the electronic ground state while the M08HX functional employed in the original article predicts an incorrect C2v geometry and energy. By combining thermodynamic data for the OH + HNO3 → H2O + NO3 reaction with spectroscopic data and results from M08HX calculations on HNO3, H2O and the OH radical, the ground state NO3 radical energy is estimated to be 37 kJ mol−1 lower than reported for the C2v geometry.

• Tomsche, Laura; Piel, Felix Maximilian; Mikoviny, Tomas; Nielsen, Claus Jørgen; Guo, Hongyu & Campuzano-Jost, Pedro [Vis alle 17 forfattere av denne artikkelen] (2023). Measurement report: Emission factors of NH3 and NHx for wildfires and agricultural fires in the United States. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 23(4), s. 2331–2343. doi: 10.5194/acp-23-2331-2023. Fulltekst i vitenarkiv Vis sammendrag

  Abstract. During the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study, the NASA DC-8 carried out in situ chemical measurements in smoke plumes emitted from wildfires and agricultural fires in the contiguous United States. The DC-8 payload included a modified proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for the fast measurement of gaseous ammonia (NH3) and a high-resolution time-of-flight aerosol mass spectrometer (AMS) for the fast measurement of submicron particulate ammonium (NH4+). We herein report data collected in smoke plumes emitted from 6 wildfires in the Western United States, 2 prescribed grassland fires in the Central United States, 1 prescribed forest fire in the Southern United States, and 66 small agricultural fires in the Southeastern United States. Smoke plumes contained double to triple digit ppb levels of NH3. In the wildfire plumes, a significant fraction of NH3 had already been converted to NH4+ at the time of sampling (≥2 h after emission). Substantial amounts of NH4+ were also detected in freshly emitted smoke from corn and rice field fires. We herein present a comprehensive set of emission factors of NH3 and NHx, with NHx=NH3+NH4+. Average NH3 and NHx emission factors for wildfires in the Western United States were 1.86±0.75 g kg−1 and 2.47±0.80 g kg−1 of fuel burned, respectively. Average NH3 and NHx emission factors for agricultural fires in the Southeastern United States were 0.89±0.58 and 1.74±0.92 g kg−1, respectively. Our data show no clear inverse correlation between modified combustion efficiency (MCE) and NH3 emissions. The observed NH3 emissions were significantly higher than measured in previous laboratory experiments in the FIREX FireLab 2016 study.

• Bunkan, Arne Joakim Coldevin; Reijrink, Nina Gwendolyn; Mikoviny, Tomas; Müller, Markus; Nielsen, Claus Jørgen & Zhu, Liang [Vis alle 7 forfattere av denne artikkelen] (2022). Atmospheric Chemistry of N-Methylmethanimine (CH<inf>3</inf>N=CH<inf>2</inf>): A Theoretical and Experimental Study. Journal of Physical Chemistry A. ISSN 1089-5639. 126(20), s. 3247–3264. doi: 10.1021/acs.jpca.2c01925. Fulltekst i vitenarkiv Vis sammendrag

  The OH-initiated photo-oxidation of N-methylmethanimine, CH3N═CH2, was investigated in the 200 m3 EUPHORE atmospheric simulation chamber and in a 240 L stainless steel photochemical reactor employing time-resolved online FTIR and high-resolution PTR-ToF-MS instrumentation and in theoretical calculations based on quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations forecast the OH reaction to primarily proceed via H-abstraction from the ═CH2 group and π-system C-addition, whereas H-abstraction from the −CH3 group is a minor route and forecast that N-addition can be disregarded under atmospheric conditions. Theoretical studies of CH3N═CH2 photolysis and the CH3N═CH2 + O3 reaction show that these removal processes are too slow to be important in the troposphere. A detailed mechanism for OH-initiated atmospheric degradation of CH3N═CH2 was obtained as part of the theoretical study. The photo-oxidation experiments, obstructed in part by the CH3N═CH2 monomer–trimer equilibrium, surface reactions, and particle formation, find CH2═NCHO and CH3N═CHOH/CH2═NCH2OH as the major primary products in a ratio 18:82 ± 3 (3σ-limit). Alignment of the theoretical results to the experimental product distribution results in a rate coefficient, showing a minor pressure dependency under tropospheric conditions and that can be parametrized k(T) = 5.70 × 10–14 × (T/298 K)3.18 × exp(1245 K/T) cm3 molecule–1 s–1 with k298 = 3.7 × 10–12 cm3 molecule–1 s–1. The atmospheric fate of CH3N═CH2 is discussed, and it is concluded that, on a global scale, hydrolysis in the atmospheric aqueous phase to give CH3NH2 + CH2O will constitute a dominant loss process. N2O will not be formed in the atmospheric gas phase degradation, and there are no indications of nitrosamines and nitramines formed as primary products.

• Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Tang, Yizhen & Wisthaler, Armin [Vis alle 15 forfattere av denne artikkelen] (2021). Atmospheric Chemistry of 2-Amino-2-methyl-1-propanol: A Theoretical and Experimental Study of the OH-Initiated Degradation under Simulated Atmospheric Conditions. Journal of Physical Chemistry A. ISSN 1089-5639. 125(34), s. 7502–7519. doi: 10.1021/acs.jpca.1c04898. Fulltekst i vitenarkiv Vis sammendrag

  The OH-initiated degradation of 2-amino-2-methyl-1-propanol [CH3C(NH2)(CH3)CH2OH, AMP] was investigated in a large atmospheric simulation chamber, employing time-resolved online high-resolution proton-transfer reaction-time-of-flight mass spectrometry (PTR-ToF-MS) and chemical analysis of aerosol online PTR-ToF-MS (CHARON-PTR-ToF-MS) instrumentation, and by theoretical calculations based on M06-2X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations reproduce the experimental rate coefficient of the AMP + OH reaction, aligning k(T) = 5.2 × 10–12 × exp (505/T) cm3 molecule–1 s–1 to the experimental value kexp,300K = 2.8 × 10–11 cm3 molecule–1 s–1. The theoretical calculations predict that the AMP + OH reaction proceeds via hydrogen abstraction from the −CH3 groups (5–10%), −CH2– group, (>70%) and −NH2 group (5–20%), whereas hydrogen abstraction from the −OH group can be disregarded under atmospheric conditions. A detailed mechanism for atmospheric AMP degradation was obtained as part of the theoretical study. The photo-oxidation experiments show 2-amino-2-methylpropanal [CH3C(NH2)(CH3)CHO] as the major gas-phase product and propan-2-imine [(CH3)2C═NH], 2-iminopropanol [(CH3)(CH2OH)C═NH], acetamide [CH3C(O)NH2], formaldehyde (CH2O), and nitramine 2-methyl-2-(nitroamino)-1-propanol [AMPNO2, CH3C(CH3)(NHNO2)CH2OH] as minor primary products; there is no experimental evidence of nitrosamine formation. The branching in the initial H abstraction by OH radicals was derived in analyses of the temporal gas-phase product profiles to be BCH3/BCH2/BNH2 = 6:70:24. Secondary photo-oxidation products and products resulting from particle and surface processing of the primary gas-phase products were also observed and quantified. All the photo-oxidation experiments were accompanied by extensive particle formation that was initiated by the reaction of AMP with nitric acid and that mainly consisted of this salt. Minor amounts of the gas-phase photo-oxidation products, including AMPNO2, were detected in the particles by CHARON-PTR-ToF-MS and GC×GC-NCD. Volatility measurements of laboratory-generated AMP nitrate nanoparticles gave ΔvapH = 80 ± 16 kJ mol–1 and an estimated vapor pressure of (1.3 ± 0.3) × 10–5 Pa at 298 K. The atmospheric chemistry of AMP is evaluated and a validated chemistry model for implementation in dispersion models is presented.

• Fagerlund, Johan; Zevenhoven, Ron; Thomassen, Jørgen; Tednes, Marius; Abdollahi, Farhang & Thomas, Laurent [Vis alle 12 forfattere av denne artikkelen] (2021). Performance of an amine-based CO2 capture pilot plant at the Fortum Oslo Varme Waste to Energy plant in Oslo, Norway. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 106, s. 1–14. doi: 10.1016/j.ijggc.2020.103242. Fulltekst i vitenarkiv Vis sammendrag

  Fortum Oslo Varme AS (FOV) decided (in July 2018) to build a 1:350 scale pilot plant to demonstrate that the selected Shell’s CANSOLV capture technology using solvent DC-103 is suitable for cleaning CO₂ from the exhaust gases of their waste to energy (WtE) plant at Klemetsrud in Oslo, Norway. This paper presents the most important measurement data and results from a pilot plant testing campaign from March to December 2019. The project stated requirements for the successful completion of the first pilot plant campaign were at least 2000 operational hours and total amine emissions lower than 0.4 ppmv on average over the last 500 h of testing. Emphasis is on the online emission measurement results both with and without an aerosol emissions mitigation system located downstream of the capture unit. The impact of perturbations in the plant operating conditions and inlet gas quality is discussed, in particular the particulates content. The pilot plant campaign achieved its primary purpose of demonstrating low amine emissions. It also produced important data on absorbent degradation in actual operation on WtE flue gas while confirming other performance parameters such as CO2 capture efficiency, steam consumption and CO2 product purity. Thus, it can be concluded that the all requirements according to objectives of the pilot campaign were successfully met.

• Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Stenstrøm, Yngve H. & Wisthaler, Armin [Vis alle 7 forfattere av denne artikkelen] (2020). Atmospheric Chemistry of Methyl Isocyanide – an Experimental and Theoretical Study. Journal of Physical Chemistry A. ISSN 1089-5639. 124(32), s. 6562–6571. doi: 10.1021/acs.jpca.0c05127. Fulltekst i vitenarkiv Vis sammendrag

  The reaction of CH3NC with OH radicals was studied in smog chamber experiments employing PTR-ToF-MS and long-path FTIR detection. The rate coefficient was determined to be kCH3NC+OH = (7.9 ± 0.6) × 10–11 cm3 molecule–1 s–1 at 298 ± 3 K and 1013 ± 10 hPa; methyl isocyanate was the sole observed product of the reaction. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ quantum chemistry calculations showing the reaction to proceed primarily via electrophilic addition to the isocyanide carbon atom. On the basis of the quantum chemical data, the kinetics of the OH reaction was simulated using a master equation model revealing the rate coefficient to be nearly independent of pressure at tropospheric conditions and having a negative temperature dependence with kOH = 4.2 × 10–11 cm3 molecule–1 s–1 at 298 K. Additional quantum chemistry calculations on the CH3NC reactions with O3 and NO3 show that these reactions are of little importance under atmospheric conditions. The atmospheric fate of methyl isocyanide is discussed.

• Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Stenstrøm, Yngve H. & Wisthaler, Armin [Vis alle 7 forfattere av denne artikkelen] (2020). Atmospheric chemistry of diazomethane – an experimental and theoretical study. Molecular Physics. ISSN 0026-8976. s. 1–8. doi: 10.1080/00268976.2020.1718227. Fulltekst i vitenarkiv Vis sammendrag

  The kinetics of the O3, OH and NO3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3 = (3.2 ± 0.4) × 10−17 and k CH2NN+OH = (1.68 ± 0.12) × 10−10 cm3 molecule−1 s−1 at 295 ± 3 K and 1013 ± 30 hPa, whereas the CH2NN + NO3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed.

• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2020). Acetonitrile/sulfuric acid/water clusters: A matrix isolation infrared and computational study. Journal of Molecular Structure. ISSN 0022-2860. 1199:126948, s. 1–5. doi: 10.1016/j.molstruc.2019.126948. Fulltekst i vitenarkiv
• Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & D´Anna, Barbara [Vis alle 14 forfattere av denne artikkelen] (2020). Experimental and Theoretical Study of the OH-Initiated Degradation of Piperazine under Simulated Atmospheric Conditions. Journal of Physical Chemistry A. ISSN 1089-5639. doi: 10.1021/acs.jpca.0c10223. Fulltekst i vitenarkiv Vis sammendrag

  The OH-initiated photo-oxidation of piperazine and 1-nitropiperazine as well as the photolysis of 1-nitrosopiperazine were investigated in a large atmospheric simulation chamber. The rate coefficient for the reaction of piperazine with OH radicals was determined by the relative rate method to be kOH-piperazine = (2.8 ± 0.6) × 10–10 cm3 molecule–1 s–1 at 307 ± 2 K and 1014 ± 2 hPa. Product studies showed the piperazine + OH reaction to proceed both via C–H and N–H abstraction, resulting in the formation of 1,2,3,6-tetrahydropyrazine as the major product and in 1-nitropiperazine and 1-nitrosopiperazine as minor products. The branching in the piperazinyl radical reactions with NO, NO2, and O2 was obtained from 1-nitrosopiperazine photolysis experiments and employed analyses of the 1-nitropiperazine and 1-nitrosopiperazine temporal profiles observed during piperazine photo-oxidation. The derived initial branching between N–H and C–H abstraction by OH radicals, kN–H/(kN–H + kC–H), was 0.18 ± 0.04. All experiments were accompanied by substantial aerosol formation that was initiated by the reaction of piperazine with nitric acid. Both primary and secondary photo-oxidation products including 1-nitropiperazine and 1,4-dinitropiperazine were detected in the aerosol particles formed. Corroborating atmospheric photo-oxidation schemes for piperazine and 1-nitropiperazine were derived from M06-2X/aug-cc-pVTZ quantum chemistry calculations and master equation modeling of the pivotal reaction steps. The atmospheric chemistry of piperazine is evaluated, and a validated chemical mechanism for implementation in dispersion models is presented.

• Hodnebrog, Øivind; Aamaas, Borgar; Fuglestvedt, Jan S.; Marston, G.; Myhre, Gunnar & Nielsen, Claus Jørgen [Vis alle 9 forfattere av denne artikkelen] (2020). Updated global warming potentials and radiative efficiencies of halocarbons and other weak atmospheric absorbers. Reviews of Geophysics. ISSN 8755-1209. 58:e2019RG000691(3), s. 1–30. doi: 10.1029/2019RG000691. Fulltekst i vitenarkiv Vis sammendrag

  Human activity has led to increased atmospheric concentrations of many gases, including halocarbons, and may lead to emissions of many more gases. Many of these gases are, on a per molecule basis, powerful greenhouse gases, although at present‐day concentrations their climate effect is in the so‐called weak limit (i.e., their effect scales linearly with concentration). We published a comprehensive review of the radiative efficiencies (RE) and global warming potentials (GWP) for around 200 such compounds in 2013 (Hodnebrog et al., 2013, https://doi.org/10.1002/rog.20013). Here we present updated RE and GWP values for compounds where experimental infrared absorption spectra are available. Updated numbers are based on a revised “Pinnock curve”, which gives RE as a function of wave number, and now also accounts for stratospheric temperature adjustment (Shine & Myhre, 2020, https://doi.org/10.1029/2019MS001951). Further updates include the implementation of around 500 absorption spectra additional to those in the 2013 review and new atmospheric lifetimes from the literature (mainly from WMO (2019)). In total, values for 60 of the compounds previously assessed are based on additional absorption spectra, and 42 compounds have REs which differ by >10% from our previous assessment. New RE calculations are presented for more than 400 compounds in addition to the previously assessed compounds, and GWP calculations are presented for a total of around 250 compounds. Present‐day radiative forcing due to halocarbons and other weak absorbers is 0.38 [0.33–0.43] W m−2, compared to 0.36 [0.32–0.40] W m−2 in IPCC AR5 (Myhre et al., 2013, https://doi.org/10.1017/CBO9781107415324.018), which is about 18% of the current CO2 forcing.

• Andersen, Niels Højmark; Klæboe, Peter; Nielsen, Claus Jørgen; Shumberger, Brendan M. & Guirgis, Gamil A. (2019). The Raman and infrared spectra, ab initio calculations and spectral assignments of 1,1-dicyclopropyl-2,2-dimethylethene (c-C3H5)2C]C(CH3)2. Journal of Molecular Structure. ISSN 0022-2860. 1195, s. 528–541. doi: 10.1016/j.molstruc.2019.05.108. Fulltekst i vitenarkiv
• Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & Eichler, Philipp [Vis alle 14 forfattere av denne artikkelen] (2018). Theoretical and experimental study on the reaction of tert-butylamine with OH radicals in the atmosphere. Journal of Physical Chemistry A. ISSN 1089-5639. 122(18), s. 4470–4480. doi: 10.1021/acs.jpca.8b01862. Fulltekst i vitenarkiv
• Mikoviny, Tomas; Nielsen, Claus Jørgen; Tan, Wen; Wisthaler, Armin; Zhu, Liang & Morken, Anne Kolstad [Vis alle 7 forfattere av denne artikkelen] (2017). Ambient Measurements of Amines by PTR-QiTOF: Instrument Performance Assessment and Results from Field Measurements in the Vicinity of TCM, Mongstad. Energy Procedia. 114, s. 1017–1021. doi: 10.1016/j.egypro.2017.03.1246. Fulltekst i vitenarkiv Vis sammendrag

  A PTR-QiTOF instrument was deployed in the field in the vicinity of the CO2 Technology Center Mongstad (TCM) for measuring amines in ambient air. The observed single-to-double-digit pptv levels of dimethylamine (DMA) and trimethylamine (TMA) are comparable to natural background values reported in the literature for these species. No indication was found that these small alkylamines stem from industrial activities at Mongstad. Monoethanolamine (MEA) was observed at single-digit pptv levels, but further analytical work is needed to validate measurements at such low concentrations. No indication was found that small enhancements in ambient MEA levels were caused by emissions from TCM. No other industrial amines (2-amino-2-methylpropanol, diethylamine and piperazine) were detected in ambient air. According to the current state of knowledge, the observed levels of amines pose no harm to human health or the environment.

• Zhu, Liang; Mikoviny, Tomas; Wisthaler, Armin & Nielsen, Claus Jørgen (2017). A Sampling Line Artifact in Stack Emission Measurement of Alkanolamine-enabled Carbon Capture Facility: Surface Reaction of Amines with Formaldehyde. Energy Procedia. 114, s. 1022–1025. doi: 10.1016/j.egypro.2017.03.1247. Fulltekst i vitenarkiv Vis sammendrag

  Laboratory experiments were carried out to study Schiff-base condensation reactions between amines and formaldehyde that occur on inlet lines of emission monitoring instruments. Primary amines and formaldehyde were found to quickly react on inlet surfaces to form the respective Schiff-base condensation products. Secondary and tertiary amines did not react with formaldehyde. Schiff-base condensation reactions between primary amines and formaldehyde were also observed to occur on the ∼110 m long inlet line that connects the absorber stack of the amine-based PCCC facility at Mongstad to the FT-IR and PTR-ToF-MS emission monitors. Emissions of primary amines and formaldehyde may be underestimated if condensation reactions of these species in inlet lines are not taken into account. The PTR-ToF-MS monitor does, however, also quantitatively detect the Schiff-base condensation products, making it straightforward to derive the correct amine and formaldehyde concentrations in the amine wash gas.

• Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; D'Anna, Barbara; Eichler, Philipp; Farren, Naomi J. & Hallquist, Mattias [Vis alle 15 forfattere av denne artikkelen] (2017). Atmospheric Chemistry of tert-butylamine and AMP. Energy Procedia. 114, s. 1026–1032. doi: 10.1016/j.egypro.2017.03.1248. Fulltekst i vitenarkiv Vis sammendrag

  The atmospheric chemistry of (CH3)3CNH2 (tert-butylamine, tBA) and (CH3)2(CH2OH)CNH2 (2-amino-2-methyl-1-propanol, AMP) has been studied by quantum chemistry methods and in photo-oxidation experiments in the EUPHORE chamber in Valencia (Spain). Aerosol formation and composition has been quantified. Yields of nitramines and other products in the photo-oxidations have been determined and complete photo-oxidation schemes including branching between the major reaction routes have been obtained.

• Andersen, Mads P Sulbaek; Kyte, Mildrid; Andersen, Simone Thirstrup; Nielsen, Claus Jørgen & Nielsen, Ole John (2017). Atmospheric Chemistry of (CF3)2CF–C≡N: A Replacement Compound for the Most Potent Industrial Greenhouse Gas, SF6. Environmental Science and Technology. ISSN 0013-936X. 51(3), s. 1321–1329. doi: 10.1021/acs.est.6b03758. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & Zhu, Liang (2016). Experimental and Theoretical Study of the OH-Initiated Photo-oxidation of Formamide. Journal of Physical Chemistry A. ISSN 1089-5639. 120(8), s. 1222–1230. doi: 10.1021/acs.jpca.6b00032. Fulltekst i vitenarkiv
• Jacquinet-Husson, Nicole; Armante, Raymond; Scott, Noëlle A.; Chédin, Alain; Crépeau, Laurent & Boutammine, Chérif [Vis alle 57 forfattere av denne artikkelen] (2016). The 2015 edition of the GEISA spectroscopic database. Journal of Molecular Spectroscopy. ISSN 0022-2852. 327, s. 31–72. doi: 10.1016/j.jms.2016.06.007. Fulltekst i vitenarkiv
• Maguta, Mihayo Musabila; Stenstrøm, Yngve & Nielsen, Claus Jørgen (2016). Kinetic and theoretical study of the nitrate (NO3) radical gas phase reactions with N‐nitrosodimethylamine and N‐nitrosodiethylamine. Journal of Physical Chemistry A. ISSN 1089-5639. 120(35), s. 6970–6977. doi: 10.1021/acs.jpca.6b05440. Fulltekst i vitenarkiv Vis sammendrag

  The reaction rates of (CH3)2NNO and (CH3CH2)2NNO with NO3 radicals were determined relative to formaldehyde (CH2O) and ethene (CH2CH2) at 298 ± 2 K and 1013 ± 10 hPa in purified air by long path FTIR spectroscopy. The reactions are too slow to be of importance at atmospheric conditions: kNO3+(CH3)2NNO = (1.47 ± 0.23) × 10−16 and kNO3+(CH3CH2)2NNO = (5.1 ± 0.4) × 10−16 cm3 molecule−1 s−1 (1σ error limits). Theoretical calculations, based on CCSD- (T*)-F12a/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ results, pre- dict the corresponding imines as the sole primary products in nitrosamine reactions with NO3 and OH radicals.

• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2016). H-Bonding of Sulfuric Acid with Its Decomposition Products: An Infrared Matrix Isolation and Computational Study of the H2SO4·H2O·SO3 Complex. Journal of Physical Chemistry A. ISSN 1089-5639. 120(20), s. 3450–3455. doi: 10.1021/acs.jpca.6b00635. Fulltekst i vitenarkiv
• Wallington, Timothy J.; Pivesso, Bruno Pasquini; Lira, Alane Moura; Anderson, James E.; Nielsen, Claus Jørgen & Andersen, Niels Højmark [Vis alle 7 forfattere av denne artikkelen] (2016). CH3Cl, CH2Cl2, CHCl3, and CCl4: Infrared spectra, radiative efficiencies, and global warming potentials. Journal of Quantitative Spectroscopy and Radiative Transfer. ISSN 0022-4073. 174, s. 56–64. doi: 10.1016/j.jqsrt.2016.01.029. Fulltekst i vitenarkiv Vis sammendrag

  Infrared spectra for the title compounds were measured experimentally in 700 Torr of air at 295 K and systematically modeled in B3LYP, M06-2X and MP2 calculations employing various basis sets. Calibrated infrared spectra over the wavenumber range 600–3500 cm−1 are reported and combined with literature data to provide spectra for use in experimental studies and radiative transfer calculations. Integrated absorption cross sections are (units of cm−1 molecule−1): CH3Cl, 660–780 cm−1, (3.89±0.19)×10−18; CH2Cl2, 650-800 cm−1, (2.16±0.11)×10−17; CHCl3, 720–810 cm−1, (4.08±0.20)×10−17; and CCl4, 730–825 cm−1, (6.30±0.31)×10−17. CH3Cl, CH2Cl2, CHCl3, and CCl4 have radiative efficiencies of 0.004, 0.028, 0.070, and 0.174 W m−2 ppb−1 and global warming potentials (100 year horizon) of 5, 8, 15, and 1775, respectively. Quantum chemistry calculations generally predict larger band intensities than the experimental values. The best agreement with experiments is obtained in MP2(Full) calculations employing basis sets of at least triple-zeta quality augmented by diffuse functions. The B3LYP functional is found ill-suited for calculating vibrational frequencies and infrared intensities of halocarbons.

• Nicovich, J. Michael; Mazumder, Shivnath B.; Laine, Patrick L.; Wine, Paul H.; Tang, Yizhen & Bunkan, Arne Joakim Coldevin [Vis alle 7 forfattere av denne artikkelen] (2015). An experimental and theoretical study of the gas phase kinetics of atomic chlorine reactions with CH3NH2, (CH3)2NH, and (CH3)3N. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 17(2), s. 911–917. doi: 10.1039/c4cp03801k. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Hetzler, Jens; Mikoviny, Tomas; Wisthaler, Armin; Nielsen, Claus Jørgen & Olzmann, Matthias (2015). The reactions of N-methylformamide and N,N-dimethylformamide with OH and their photo-oxidation under atmospheric conditions: experimental and theoretical studies. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 17(10), s. 7046–7059. doi: 10.1039/C4CP05805D. Fulltekst i vitenarkiv Vis sammendrag

  The reactions of OH radicals with CH3NHCHO (N-methylformamide, MF) and (CH3)2NCHO (N,N-dimethylformamide, DMF) have been studied by experimental and computational methods. Rate coefficients were determined as a function of temperature (T = 260–295 K) and pressure (P = 30–600 mbar) by the flash photolysis/laser-induced fluorescence technique. OH radicals were produced by laser flash photolysis of 2,4-pentanedione or tert-butyl hydroperoxide under pseudo-first order conditions in an excess of the corresponding amide. The rate coefficients obtained show negative temperature dependences that can be parameterized as follows: kOH+MF = (1.3 ± 0.4) × 10−12 exp(3.7 kJ mol−1/(RT)) cm3 s−1 and kOH+DMF = (5.5 ± 1.7) × 10−13 exp(6.6 kJ mol−1/(RT)) cm3 s−1. The rate coefficient kOH+MF shows very weak positive pressure dependence whereas kOH+DMF was found to be independent of pressure. The Arrhenius equations given, within their uncertainty, are valid for the entire pressure range of our experiments. Furthermore, MF and DMF smog-chamber photo-oxidation experiments were monitored by proton-transfer-reaction time-of-flight mass spectrometry. Atmospheric MF photo-oxidation results in 65% CH3NCO (methylisocyanate), 16% (CHO)2NH, and NOx-dependent amounts of CH2[double bond, length as m-dash]NH and CH3NHNO2 as primary products, while DMF photo-oxidation results in around 35% CH3N(CHO)2 as primary product and 65% meta-stable (CH3)2NC(O)OONO2 degrading to NOx-dependent amounts of CH3N[double bond, length as m-dash]CH2 (N-methylmethanimine), (CH3)2NNO (N-nitroso dimethylamine) and (CH3)2NNO2 (N-nitro dimethylamine). The potential for nitramine formation in MF photo-oxidation is comparable to that of methylamine whereas the potential to form nitrosamine and nitramine in DMF photo-oxidation is larger than for dimethylamine. Quantum chemistry supported atmospheric degradation mechanisms for MF and DMF are presented. Rate coefficients and initial branching ratios calculated with statistical rate theory based on molecular data from quantum chemical calculations at the CCSD(T*)-F12a/aug-cc-pVTZ//MP2/aug-cc-pVTZ level of theory show satisfactory agreement with the experimental results. It turned out that adjustment of calculated threshold energies by 0.2 to 8.8 kJ mol−1 lead to agreement between experimental and predicted results.

• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2015). H-Bonding of Formic Acid with Its Decomposition Products: A Matrix Isolation and Computational Study of the HCOOH/CO and HCOOH/CO2 Complexes. Journal of Physical Chemistry A. ISSN 1089-5639. 119(31), s. 8497–8502. doi: 10.1021/acs.jpca.5b05214. Fulltekst i vitenarkiv
• Nilsson, Elna J. K.; Heimdal, Jimmy; Bache-Andreassen, Lihn; Johnson, Matthew S. & Nielsen, Claus Jørgen (2015). Tropospheric Photolysis Rates of the Acetaldehyde Isotopologues CD3CHO and CD3CDO Relative to CH3CHO Measured at the European Photoreactor Facility. Journal of Physical Chemistry A. ISSN 1089-5639. 119(11), s. 2562–2567. doi: 10.1021/jp509050d. Fulltekst i vitenarkiv
• Nielsen, Claus Jørgen; Klæboe, Peter; Andersen, Niels Højmark; Guirgis, Gamil A.; Hickman, Daniel V. & Morris, Tamia B. (2015). Infrared and Raman spectra, DFT-calculations and spectral assignments of 1,1,3,3,5,5-hexafluoro-1,3,5-trisilacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1099, s. 399–406. doi: 10.1016/j.molstruc.2015.05.065. Fulltekst i vitenarkiv
• Guirgis, Gamil A.; Dukes, Horace W.; Wyatt, Justin K.; Nielsen, Claus Jørgen; Horn, Anne & Aleksa, Valdemaras [Vis alle 7 forfattere av denne artikkelen] (2015). Vibrational spectra, quantum chemical calculations and spectral assignments of 1,1-difluoro-1-silacyclohexane Dedicated to Professor Benjamin J. van der Veken, University of Antwerp, Belgium on the occasion of his 65 years birthday. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. ISSN 1386-1425. 136, s. 51–57. doi: 10.1016/j.saa.2013.10.058. Fulltekst i vitenarkiv
• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2015). Hydrogen bonding in the sulfuric acid-methanol-water system: A matrix isolation and computational study. Journal of Physical Chemistry A. ISSN 1089-5639. 119(11), s. 2271–2280. doi: 10.1021/jp505965z. Fulltekst i vitenarkiv
• Andersen, Niels Højmark; Klæboe, Peter; Nielsen, Claus Jørgen; Guirgis, Gamil A.; Overby, Jason S. & Askarian, Sahand M. (2014). Infrared and Raman spectra, DFT calculations and spectral assignments of 1,3,5-trisilacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1076, s. 419–425. doi: 10.1016/j.molstruc.2014.07.077. Fulltekst i vitenarkiv
• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2014). Trimethylamine/sulfuric acid/water clusters: A matrix isolation infrared study. Journal of Physical Chemistry A. ISSN 1089-5639. 118(6), s. 1004–1011. doi: 10.1021/jp410922x. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Tang, Yizhen; Sellevåg, Stig Rune & Nielsen, Claus Jørgen (2014). Atmospheric Gas Phase Chemistry of CH2═NH and HNC. A First-Principles Approach. Journal of Physical Chemistry A. ISSN 1089-5639. 118(28), s. 5279–5288. doi: 10.1021/jp5049088. Fulltekst i vitenarkiv
• Maguta, Mihayo Musabila; Aursnes, Marius; Bunkan, Arne Joakim Coldevin; Edelen, Katie; Mikoviny, Tomas & Nielsen, Claus Jørgen [Vis alle 9 forfattere av denne artikkelen] (2014). Atmospheric fate of nitramines: An experimental and theoretical study of the OH reactions with CH&lt;sub&gt;3&lt;/sub&gt;NHNO&lt;sub&gt;2&lt;/sub&gt; and (CH&lt;sub&gt;3&lt;/sub&gt;) &lt;sub&gt;2&lt;/sub&gt;NNO&lt;sub&gt;2&lt;/sub&gt;. Journal of Physical Chemistry A. ISSN 1089-5639. 118(19), s. 3450–3462. doi: 10.1021/jp500305w. Fulltekst i vitenarkiv
• Jankowski, Mikolaj; Olsen, Raymond; Nielsen, Claus Jørgen; Thomassen, Yngvar & Molander, Pål (2014). The applicability of proton transfer reaction-mass spectrometry (PTR-MS) for determination of isocyanic acid (ICA) in work room atmospheres. Environmental Science: Processes & Impacts. ISSN 2050-7887. 16(10), s. 2423–2431. doi: 10.1039/c4em00363b. Fulltekst i vitenarkiv Vis sammendrag

  A method is presented for the real-time quantitative determination of isocyanic acid (ICA) in air using proton transfer reaction-mass spectrometry (PTR-MS). Quantum mechanical calculations were performed to establish the ion-polar molecule reaction rate of ICA and other isocyanates. The PTR-MS was calibrated against different ICA air concentrations and humidity conditions using Fourier transform-infrared spectroscopy (FT-IR) as quantitative reference. Based on these experiments a simple humidity dependant model was derived for correction of the PTR-MS response for ICA. The corrected PTR-MS data was linearly correlated (R2 > 0.99) with the data acquired by FT-IR. The PTR-MS instrumental limit of detection (LOD) for ICA was 2.3 ppb. Humid atmospheres resulted in LODs of 3.4 and 7.8 ppb, at an absolute humidity (AH) of 4.0 and 15.5 g m−3, respectively. Furthermore, off-line sampling using denuder and impinger samplers using di-n-butylamine (DBA) as derivatization reagent was compared with PTR-MS measurements in a dynamically generated standard ICA atmosphere. Denuder (n = 4) and impinger (n = 4) sampling subsequent to liquid chromatography mass spectrometry (LC-MS) determination compared to corrected PTR-MS data resulted in recoveries of 79.6 (8.1% RSD) and 99.9 (9.3% RSD) %, respectively. Measurements of ICA from thermally decomposed cured 1,6-hexamethylene diisocyanate (HDI)-paint was performed using PTR-MS and denuder (n = 3) sampling. The relation between the average ICA responses using denuders (34.4 ppb) and PTR-MS (42.6 ppb) was 80.6%, which coincided well with the relative recovery obtained from the controlled laboratory experiments using dynamically generated ICA atmospheres (79.6%). The variability in ICA air concentration during the welding process (170% RSDPTR-MS) illustrated the need for real-time measurements.

• Hodnebrog, Øivind; Etminan, Maryam; Fuglestvedt, Jan S.; Marston, George; Myhre, Gunnar & Nielsen, Claus Jørgen [Vis alle 8 forfattere av denne artikkelen] (2013). Global warming potentials and radiative efficiencies of halocarbons and related compounds: A comprehensive review. Reviews of Geophysics. ISSN 8755-1209. 51(2), s. 300–378. doi: 10.1002/rog.20013. Fulltekst i vitenarkiv
• Klæboe, Peter; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A.; Overby, Jason S. & Aleksa, Valdemaras (2013). Raman and infrared spectra, quantum chemical calculations, conformations and spectral assignments of 1-chloro-1-methyl-1-silacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1047, s. 282–291. doi: 10.1016/j.molstruc.2013.05.003. Fulltekst i vitenarkiv
• Klæboe, Peter; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A.; Overby, Jason S. & Aleksa, Valdemaras (2013). Raman and infrared spectra, quantum chemical calculations, conformational and spectral assignments of 1-chloro-1-methyl-1-silacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1047, s. 282–291. doi: 10.1016/j.molstruc.2013.05.003. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Liang, Chi-Hsiu; Pilling, Michael J. & Nielsen, Claus Jørgen (2013). Theoretical and experimental study of the OH radical reaction with HCN. Molecular Physics. ISSN 0026-8976. 111(9-11), s. 1589–1598. doi: 10.1080/00268976.2013.802036. Fulltekst i vitenarkiv
• Onel, L.; Thonger, L.; Blitz, M.A.; Seakins, P.W.; Bunkan, Arne Joakim Coldevin & Solimannejad, Mohammad [Vis alle 7 forfattere av denne artikkelen] (2013). Gas-Phase Reactions of OH with Methyl Amines in the Presence or Absence of Molecular Oxygen. An Experimental and Theoretical Study. Journal of Physical Chemistry A. ISSN 1089-5639. 117(41), s. 10736–10745. doi: 10.1021/jp406522z. Fulltekst i vitenarkiv
• Klæboe, Peter; Horn, Anne; Nielsen, Claus Jørgen; Aleksa, Valdemaras; Guirgis, Gamil A. & Wyatt, Justin K. [Vis alle 7 forfattere av denne artikkelen] (2013). Infrared and Raman spectra, conformations, quantum chemical calculations and spectral assignments of 1-methyl-1-silacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1034, s. 207–215. doi: 10.1016/j.molstruc.2012.10.045. Fulltekst i vitenarkiv
• Tang, Yizhen & Nielsen, Claus Jørgen (2013). Theoretical Study on the Formation and Photolysis of Nitrosamines (CH3CH2NHNO and (CH3CH2)(2)NNO) under Atmospheric Conditions. Journal of Physical Chemistry A. ISSN 1089-5639. 117(1), s. 126–132. doi: 10.1021/jp307812m. Fulltekst i vitenarkiv
• Koeijer, Gelein de; Talstad, Vibeke Randgaard; Nepstad, Sissel; Tønnesen, Dag Arild; Falk-Pedersen, Olav & Maree, Yolandi [Vis alle 7 forfattere av denne artikkelen] (2013). Health risk analysis for emissions to air from CO2 Technology Centre Mongstad. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 18, s. 200–207. doi: 10.1016/j.ijggc.2013.07.010. Fulltekst i vitenarkiv
• Zhu, Liang; Schade, Gunnar Wolfgang & Nielsen, Claus Jørgen (2013). Real-time monitoring of emissions from monoethanolamine-based industrial scale carbon capture facilities. Environmental Science and Technology. ISSN 0013-936X. 47(24), s. 14306–14314. doi: 10.1021/es4035045. Fulltekst i vitenarkiv
• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2012). H-Bonded Clusters in the Trimethylamine/Water System: A Matrix Isolation and Computational Study. Journal of Physical Chemistry A. ISSN 1089-5639. 116(16), s. 4089–4096. doi: 10.1021/jp3020035. Fulltekst i vitenarkiv
• Tang, Yizhen; Hanrath, Michael & Nielsen, Claus Jørgen (2012). Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)(2)NNO. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 14(47), s. 16365–16370. doi: 10.1039/c2cp42219k. Fulltekst i vitenarkiv
• Aleksa, Valdemaras; Guirgis, Gamil A.; Horn, Anne; Klæboe, Peter; Liberatore, Richard J. & Nielsen, Claus Jørgen (2012). Vibrational spectra, conformations, quantum chemical calculations and spectral assignments of 1-chloro-1-silacyclohexane. Vibrational Spectroscopy. ISSN 0924-2031. 61, s. 167–175. doi: 10.1016/j.vibspec.2012.02.021. Fulltekst i vitenarkiv
• Guirgis, Gamil A.; Nielsen, Claus Jørgen; Horn, Anne; Aleksa, Valdemaras & Klæboe, Peter (2012). Infrared and Raman spectra, DFT-calculations and spectral assignments of silacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1023, s. 189–196. doi: 10.1016/j.molstruc.2012.04.086. Fulltekst i vitenarkiv
• Nielsen, Claus Jørgen; Herrmann, Hartmut & Weller, Christian (2012). Atmospheric chemistry and environmental impact of the use of amines in carbon capture and storage (CCS). Chemical Society Reviews. ISSN 0306-0012. 41(19), s. 6684–6704. doi: 10.1039/c2cs35059a. Fulltekst i vitenarkiv
• Klæboe, Peter; Aleksa, Valdemaras; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A. & Johnston, Merrick H. (2012). Infrared and Raman spectra, conformations, ab initio calculations and spectral assignments of 1-fluoro-1-silacyclohexane. Journal of Molecular Structure. ISSN 0022-2860. 1015, s. 120–128. doi: 10.1016/j.molstruc.2012.02.016. Fulltekst i vitenarkiv
• Tang, Yizhen & Nielsen, Claus Jørgen (2012). A systematic theoretical study of imines formation from the atmospheric reactions of RnNH2-n with O-2 and NO2 (R = CH3 and CH3CH2; n=1 and 2). Atmospheric Environment. ISSN 1352-2310. 55, s. 185–189. doi: 10.1016/j.atmosenv.2012.02.094. Fulltekst i vitenarkiv
• Salo, Kent; Westerlund, Jonathan; Andersson, Patrik Urban; Nielsen, Claus Jørgen; D'Anna, Barbara & Hallquist, Mattias (2011). Thermal Characterization of Aminium Nitrate Nanoparticles. Journal of Physical Chemistry A. ISSN 1089-5639. 115(42), s. 11671–11677. doi: 10.1021/jp204957k. Fulltekst i vitenarkiv
• Klæboe, Peter; Horn, Anne; Nielsen, Claus Jørgen & Guirgis, Gamil A. (2011). The infrared and Raman spectra, ab initio calculations and spectral assignments of cyclopropylmethyl dichlorosilane (c-C3H5)SiCl2CH3. Vibrational Spectroscopy. ISSN 0924-2031. 56(2), s. 136–145. doi: 10.1016/j,vibspec.2011.01.006. Fulltekst i vitenarkiv
• Nielsen, Claus Jørgen; D'Anna, Barbara; Dye, Christian Jarle; Graus, Martin; Karl, Matthias & King, Stephanie [Vis alle 12 forfattere av denne artikkelen] (2011). Atmospheric chemistry of 2-aminoethanol (MEA). Energy Procedia. 4, s. 2245–2252. doi: 10.1016/j.egypro.2011.02.113. Fulltekst i vitenarkiv
• Rozenberg, Mark; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2011). Complexes of Molecular and Ionic Character in the Same Matrix Layer: Infrared Studies of the Sulfuric Acid/Ammonia System. Journal of Physical Chemistry A. ISSN 1089-5639. 115(23), s. 5759–5766. doi: 10.1021/jp107369r. Fulltekst i vitenarkiv
• Usseglio, Sandro; Thorshaug, Knut; Karlsson, Arne; Dahl, Ivar M.; Nielsen, Claus Jørgen & Jens, Klaus-Joachim [Vis alle 7 forfattere av denne artikkelen] (2010). In Situ Infrared Emission Spectroscopy for Quantitative Gas-Phase Measurement Under High Temperature Reaction Conditions: An Analytical Method for Methane by Means of an Innovative Small-Volume Flowing Cell. Applied Spectroscopy. ISSN 0003-7028. 64(2), s. 141–148. Fulltekst i vitenarkiv Vis sammendrag

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• Rozenberg, M; Loewenschuss, Aharon & Nielsen, Claus Jørgen (2010). Spectral shifts of matrix isolated species as criteria for acid-base interactions with solid Xe. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 12(16), s. 4024–4031. doi: 10.1039/b922952c. Fulltekst i vitenarkiv
• Klæboe, Peter; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A. & Wurrey, C. J. (2010). Infrared and Raman spectra, conformations, ab initio calculations and spectral assignments of ethylmethyldichlorogermane. Journal of Molecular Structure. ISSN 0022-2860. 976(1-3), s. 105–114. doi: 10.1016/j.molstruc.2010.02.030. Fulltekst i vitenarkiv
• Ryan, Susan M & Nielsen, Claus Jørgen (2010). Global Warming Potential of Inhaled Anesthetics: Application to Clinical Use. Anesthesia and Analgesia. ISSN 0003-2999. 111(1), s. 92–98. doi: 10.1213/ANE.0b013e3181e058d7. Fulltekst i vitenarkiv
• Morozov, I.; Nielsen, Claus Jørgen; Morozova, O.; Vasiliev, E. & Loukhovitskaya, E.E. (2010). Reactions of chloroethenes with atomic chlorine in air at atmospheric pressure. Russian chemical bulletin. ISSN 1066-5285. 59(4), s. 754–760. doi: 10.1007/s11172-010-0158-4. Fulltekst i vitenarkiv
• Klæboe, Peter; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A. & Witkowski, Witold (2010). Vibrational spectra, conformational equilibrium, ab initio calculations and spectral assignments of ethylmethylgermane. Vibrational Spectroscopy. ISSN 0924-2031. 54(1), s. 56–64. doi: 10.1016/j.vibspec.2010.06.005. Fulltekst i vitenarkiv
• Durig, James R.; Panikar, Savita S.; Guirgis, Gamil A.; Gounev, Todor K.; Klæboe, Peter & Horn, Anne [Vis alle 10 forfattere av denne artikkelen] (2010). Conformational stability, r(0) structural parameters, barriers to internal rotation, vibrational assignments and ab initio calculations of c-C3H5GeH2CH3. Journal of Molecular Structure. ISSN 0022-2860. 969(1-3), s. 55–68. doi: 10.1016/j.molstruc.2010.01.042. Fulltekst i vitenarkiv
• Klæboe, Peter; Nielsen, Claus Jørgen; Horn, Anne; Guirgis, Gamil A. & Kilway, K. V. (2009). Vibrational spectroscopic studies, conformations and ab initio calculations of 1,2-bis(trifluorosilyl)ethane (CF3CH2CH2CF3). Journal of Raman Spectroscopy. ISSN 0377-0486. 40(12), s. 2111–2122. doi: 10.1002/jrs.2380. Fulltekst i vitenarkiv
• Nilsson, EJK; Bache-Andreassen, Lihn; Johnson, MS & Nielsen, Claus Jørgen (2009). Relative Tropospheric Photolysis Rates of Acetaldehyde and Formaldehyde Isotopologues Measured at the European Photoreactor Facility. Journal of Physical Chemistry A. ISSN 1089-5639. 113(15), s. 3498–3504. doi: 10.1021/jp811113c. Fulltekst i vitenarkiv
• Nilsson, EJK; Johnson, MS & Nielsen, Claus Jørgen (2009). Isotope Effects in the Reactions of Chloroform Isotopologues with Cl, OH, and OD. Journal of Physical Chemistry A. ISSN 1089-5639. 113(9), s. 1731–1739. doi: 10.1021/jp807233x. Fulltekst i vitenarkiv
• Sobron, Pablo; Sobron, F; Eide, Ulrich; Nielsen, Claus Jørgen & Rull, F (2009). Model-Based Measurements of Diffusion of Sulfuric Acid into Water Using Raman Spectroscopy. Applied Spectroscopy. ISSN 0003-7028. 63(12), s. 1382–1388. Fulltekst i vitenarkiv
• Feilberg, KL; Gruber-Stadler, Margret; Johnson, MS; Muhlhauser, M & Nielsen, Claus Jørgen (2008). 13C, O-18, and D Fractionation Effects in the Reactions of CH3OH Isotopologues with Cl and OH Radicals. Journal of Physical Chemistry A. ISSN 1089-5639. 112(44), s. 11099–11114. doi: 10.1021/jp805643x. Fulltekst i vitenarkiv
• Horn, Anne; Klæboe, Peter; Nielsen, Claus Jørgen & Guirgis, GA (2008). Vibrational spectra, conformations, ab initio calculations and vibrational assignments of 3-pentyn-2-ol. Journal of Molecular Structure. ISSN 0022-2860. 879, s. 102–112. doi: 10.1016/j.molstruc.2007.08.017. Fulltekst i vitenarkiv
• Nielsen, Claus Jørgen; Horn, Anne; Klæboe, Peter & Guirgis, GA (2008). Vibrational spectra, ab initio calculations and vibrational assignments of 3-butyn-1-ol. Journal of Molecular Structure. ISSN 0022-2860. 886, s. 90–102. doi: 10.1016/j.molstruc.2007.11.002. Fulltekst i vitenarkiv
• Marinkovic, M; Gruber-Stadler, Margret; Nicovich, JM; Soller, R; Mulhauser, M & Wine, PH [Vis alle 8 forfattere av denne artikkelen] (2008). Experimental and Theoretical Study of the Carbon-13 and Deuterium Kinetic Isotope Effects in the Cl and OH Reactions of CH3F. Journal of Physical Chemistry A. ISSN 1089-5639. 112(48), s. 12416–12429. doi: 10.1021/jp807609d. Fulltekst i vitenarkiv
• Solimannejad, Mohammad; Nielsen, Claus Jørgen & Scheiner, S (2008). Complexes pairing aliphatic amines with hydroxyl and hydroperoxyl radicals: A computational study. Chemical Physics Letters. ISSN 0009-2614. 466(4-6), s. 136–140. doi: 10.1016/j.cplett.2008.10.060. Fulltekst i vitenarkiv
• Gruber-Stadler, Margret; Muhlhauser, M; Sellevag, SR & Nielsen, Claus Jørgen (2008). A quantum chemistry study of the Cl atom reaction with formaldehyde. Journal of Physical Chemistry A. ISSN 1089-5639. 112. doi: 10.1021/jp053833. Fulltekst i vitenarkiv
• Kovacs, A; Izvekov, V; Keresztury, G; Nielsen, Claus Jørgen & Klæboe, Peter (2007). Vibrational spectroscopic study of 2-fluorophenol and 2,3,5,6-tetrafluorohydroquinone. Chemical Physics. ISSN 0301-0104. 335, s. 205–214. doi: 10.1016/j.chemphys.2007.04.018. Fulltekst i vitenarkiv
• Mugnai, M; Cardini, G; Schettino, V & Nielsen, Claus Jørgen (2007). Ab initio molecular dynamics study of aqueous formaldehyde and methanediol. Molecular Physics. ISSN 0026-8976. 105, s. 2203–2210. doi: 10.1080/00268970701513864. Fulltekst i vitenarkiv
• Guirgis, GA; Mazzone, PM; Pasko, DN; Klæboe, Peter; Horn, Anne & Nielsen, Claus Jørgen (2007). Infrared and Raman spectra, conformations, ab initio calculations and spectral assignments of 1,3-disilabutane (SiH3CH2SiH2CH3). Journal of Raman Spectroscopy. ISSN 0377-0486. 38. doi: 10.1002/jrs.1745. Fulltekst i vitenarkiv
• Sellevåg, Stig Rune; D'Anna, Barbara & Nielsen, Claus Jørgen (2007). Infrared Absorption Cross-Sections and Estimated Global Warming Potentials of CF3CH2CH2OH, CHF2CF2CH2OH, CF3CF2CH2OH, CF3CHFCF2CH2OH, and CF3CF2CF2CH2OH. Asian Chemistry Letters. ISSN 0971-9822. 11, s. 33–40. Fulltekst i vitenarkiv
• Sobron, P.; Rull, F.; Sobron, F.; Sanz, A.; Medina, J.L. & Nielsen, Claus Jørgen (2007). Raman spectroscopy of the system iron(III)-sulfuric acid-water: an approach to Tinto River's (Spain) hydrogeochemistry. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. ISSN 1386-1425. 68(4), s. 1138–1142. doi: 10.1016/j.saa.2007.06.044. Fulltekst i vitenarkiv
• Zakharov, N. V.; Johnson, M. S.; Nicolaisen, F. M.; Nielsen, Claus Jørgen; Tsyganenko, A. A. & Woldbaek, T (2007). Infrared absorption cross-sections of 1,1-dichloro-, cis- and trans-1,2-dichloro-, trichloro- and tetrachloroethene. Asian Chemistry Letters. ISSN 0971-9822. 11, s. 5–9. Fulltekst i vitenarkiv
• Gruber-Stadler, Margret; Mühlhäuser, Max; Nielsen, Claus Jørgen; Schnell, N & Peyerimhoff, S. D. (2007). Ab initio MRD-CI investigation of the electronic spectrum of dibromomethanol, Br2CHOH. Asian Chemistry Letters. ISSN 0971-9822. 11, s. 25–32. Fulltekst i vitenarkiv
• Sobron, P; Rull, F; Sobron, F; Sanz, A; Medina, J & Nielsen, Claus Jørgen (2007). Modeling the physico-chemistry of acid sulfate waters through Raman spectroscopy of the system FeSO4-H2SO4-H2O. Journal of Raman Spectroscopy. ISSN 0377-0486. 38. doi: 10.1002/jrs.1729. Fulltekst i vitenarkiv

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• Flatval, Jonas; Berg, Henriette Engen; Lillerud, Karl Petter; Olsbye, Unni; Nielsen, Claus Jørgen & Wilson, Steven Ray Haakon [Vis alle 7 forfattere av denne artikkelen] (2020). Retention of nitramines on UiO-66 ZrMOF materials and silica-based reversed phase materials. Fulltekst i vitenarkiv
• Sätra, Jenny Marie Skytte Af; Nielsen, Claus Jørgen; Bavel, Albert Van; Lundanes, Elsa & Wilson, Steven Ray Haakon (2018). Developing procedures for trace analysis of small amines in water, using LC-MS and GC-MS. Fulltekst i vitenarkiv
• Vogt, Rolf David; Zhu, Liang & Nielsen, Claus Jørgen (2018). Air pollution in big cities: New challenges from Carbon Capture. Fulltekst i vitenarkiv
• Hodnebrog, Øivind; Etminan, Maryam; Fuglestvedt, Jan S.; Marston, George; Myhre, Gunnar & Nielsen, Claus Jørgen [Vis alle 8 forfattere av denne artikkelen] (2014). Global Warming Potentials and Radiative Efficiencies of halocarbons and related compounds: A comprehensive review. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Hetzler, Jens; Nielsen, Claus Jørgen & Olzmann, Matthias (2014). Experimental and theoretical study of the reactions of OH radicals with N-methylformamide and N,N-dimethylformamide. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin & Nielsen, Claus Jørgen (2014). Can you Trust Quantum Chemical Methods to Predict the Atmospheric Chemistry of Amines and Related Compounds? Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin; Hetzler, Jens; Nielsen, Claus Jørgen & Matthias, Olzmann (2014). Kinetics of the reactions of OH radicals with N-methylformamide and N,N-dimethylformamide. Fulltekst i vitenarkiv
• Bunkan, Arne Joakim Coldevin & Nielsen, Claus Jørgen (2014). What is so special about the atmospheric chemistry of amines, imines and amides? Fulltekst i vitenarkiv
• Tan, Wen; Wisthaler, Armin & Nielsen, Claus Jørgen (2022). The Atmospheric Fate of Selected Amines Emitted from Carbon Capture Facilities. Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The climate crisis necessitates urgent decarbonisation, which can only be achieved through a variety of technologies and solutions. One of them is the chemical capture of CO2 released from industrial point sources and its storage in subsea formations. On an industrial scale, CO2 is currently captured via reaction with amines, which are small organic molecules that “bind” the CO2 in the flue gas and thereby prevent it from entering the atmosphere. However, in this process trace amounts of amines are released into the atmosphere, where they can form particles and other air pollutants (e.g., nitrosamines) that are harmful to human health and the environment. In my work, I have initially explored the capability of an ultra-sensitive mass spectrometer to detect traces of amines in the atmosphere. I have furthermore studied the degradation of three amines (tert-butylamine, 2-Amino-2-methyl-1-propanol, and piperazine) under simulated atmospheric conditions in a large outdoor chamber. The products formed during atmospheric degradation were investigated using state-of-the-art theoretical and experimental methods. One of the main findings was that amines very efficiently form particles in the atmosphere. I have, for the first time, used an advanced mass spectrometer to characterize the chemical composition of the particles formed from the breakdown of amines.

• Nielsen, Claus Jørgen (2022). GWP and ODP for five new human-made chemicals detected in Arctic air. Miljødirektoratet. Fulltekst i vitenarkiv
• Flatval, Jonas; Lundanes, Elsa; Wilson, Steven Ray Haakon; Olsbye, Unni; Nielsen, Claus Jørgen & Berg, Henriette Engen (2020). Retention of nitramines on silica-based reversed phase materials and UiO-66 MOF materials. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Capturing and storing of CO2 can reduce the emissions of CO2 in the atmosphere. However, such facilities may emit amines that can be transformed into the potentially carcinogenic nitramines dimethylnitramine (DMA-NO2), monoethanolnitramine (MEA-NO2) and monomethylnitramine (MMA-NO2) which may be released into the environment. Presently, methods for trace determination of these compounds are lacking. The goal of the study was to find a material that can give sufficient retention to provide an enrichment of the nitramines before liquid chromatography electrospray ionization-mass spectrometry determination. The retention of the nitramines was examined on various C18 materials and the metal-organic frameworks UiO-66 and UiO-66 1,4-benzenedicarboxylate-NH2 (UiO-66-NH2), which were packed in 100 µm inner diameter columns. Of the tested materials, UiO-66-NH2 showed the highest retention factors for the nitramines. UiO-66-NH2 with 0.1% formic acid adjusted to pH 7 as mobile phase gave the best compromise of retention factors for DMA-NO2 and MEA-NO2, as the intended liquid chromatography-mass spectrometry method was evaluated for DMA-NO2 and MEA-NO2 only. MMA-NO2 had the highest retention factor on UiO-66-NH2 with 0.05% dibutylamine in the mobile phase. In conclusion, the retention factors achieved were in general higher on the UiO-66 materials than on the C18 materials. However, the retention obtained is probably not large enough to give limit of quantification down to 4 ng/L, albeit, not tested, due to extraordinary circumstances.

• Reijrink, Nina Gwendolyn; Nielsen, Claus Jørgen & Wisthaler, Armin (2017). Theoretical and experimental studies of intermediates in the atmospheric degradation of imines: Degradation of methyl methanimine and N-methyl ethanimine by OH radicals. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Amine-based CO2 capture has been suggested as a way to mitigate global warming. This project aims to improve the understanding of the atmospheric photo-oxidation of two of the simplest imines by OH radicals. Laboratory studies on methyl methanimine and N-methyl ethanimine have been performed in the smog chamber at the University of Oslo and the mechanism for the photo-oxidation of N-methyl ethanimine was further studied by using quantum chemical calculations. M06-2X density functional theory and explicitly correlated coupled cluster theory were used to determine the stationary points on the potential energy surface of the reaction of N-methyl ethanimine with OH. Hydrogen abstraction from the methylene site and from the N-methyl group are predicted to be the most important pathways. The calculated rate constant for the reaction between N-methyl ethanimine and OH at 298 K was kOH,t = 6.4 × 10-13 cm3 molecule1 s-1 when tunnelling was explicitly included and kOH,nt = 5.4 × 10-13 cm3 molecule-1 s-1 without including tunnelling. Subsequent reactions were modelled with M06-2X density functional theory, which predicted N-methyleneacetamide (CH3C(O)N=CH2) and N-ethylideneformamide (CH3CH=NCHO) as the major products. The laboratory studies show that both compounds are present as a trimer during the photooxidation laboratory experiments, meaning that their results cannot be used to verify the theoretical results. The laboratory experiments will have to be repeated whilst the smog chamber is heated to assure that the imines of interest are present as monomers.

• Foseid, Lena; Vogt, Rolf David; Nielsen, Claus Jørgen; Lundanes, Elsa & Gundersen, Cathrine Brecke (2015). Determination of MEA-nitramine in Soil Water and Assessing the Sorption Potential of MEA-nitramine to Soil. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Small amounts of amines are emitted with the flue gas from amine based carbon capture plants. The amines atmospheric degradation have been studied in detail. The environmental impact of the degradation products, e.g. the possibly carcinogenic and mutagenic nitramines, is however insufficiently studied. This thesis investigates the capacity of nitramines to sorb to soil, depending on the soils physiochemical characteristics. To accomplish this, the analytical challenges with regards to determination of nitramines in soil water had to be solved. Soil samples were collected in the vicinity of Technology Center Mongstad (TCM) (~15 km) as this is a possible future deposition site for nitramines. The sampling sites were chosen with the aim of collecting soils with different physiochemical properties, with special emphasis on the content of soil organic matter and soil texture. All of the collected soil samples (n=16) were analysed for explanatory parameters expected to influence soil sorption, such as organic matter (OM) content, dissolved natural organic matter (DNOM) leached from the soil, texture, mineralogy, pH and conductivity. A selection of the samples (n=5) were used in soil sorption experiments to assess the sorption potential of N-Nitroethanolamine (MEA-nitramine). A batch experimental set-up was used, and sorption was measured as loss of MEA-nitramine from the aqueous phase after being added at known concentrations (24 h equilibrium). For these samples, elemental composition was also determined. Possible correlations between the sorption coefficients and the soils physiochemical characteristics were assessed. Determination of MEA-nitramine in soil water with LC-MS/MS proved to be a challenge due to matrix effects. Different calibration methods with and without matrix matched calibration solutions were tested. Another nitramine, N-nitromethylamine (MMA-nitramine), was tested as internal standard. Additionally, a couple of sample pretreatment techniques were tested to try and separate the analyte from the matrix (solid phase extraction (SPE), filtration). Sorption partitioning coefficients between soil and aqueous phase were determined (Kd) and the results imply that a significant amount of MEA-nitramine will remain in the aqueous phase. Correlation between the partition coefficients for the five studied soils and the soils OM content was observed (r > 0.788). Loss of internal standard (MMA-nitramine) was also observed, this loss correlated strongly with the DNOM concentration in the sample supernatant (r = 0.9924), implying that sorption to DNOM could be important. The relation between sorption and OM content implies that sorption will generally be higher in the top soil (organic) horizons than in the lower (mineral) soil horizons. As deposition of atmospherically formed nitramines will be to the soil surface, this can serve to hinder mobility. The analytical determination method for nitramines in soil water was improved, although not considered satisfactory at the end of the study. Major improvement resulted from the used of matrix matched calibration curves, which compensate for both ion suppression/enhancement effects and possible sorption to DNOM. Even though this is time- and labour consuming, the method was proven more successful than attempts made to separate the analyte from the matrix prior to analysis. The used of MMA-nitramine as an internal standard for determination of MEA-nitramine was not successful, possibly due to the difference in retention time and therefore possible different effect from the matrix components. An isotope-labelled internal standard should therefore be acquired. Investigation into other sample pretreatments could also be of interest. Note that previously reported sorption partition coefficients for sorption of nitramines to soil could be inaccurate if matrix matched calibration curves were not employed.

• Bunkan, Arne Joakim Coldevin; Nielsen, Claus Jørgen; Uggerud, Einar & Helgaker, Trygve (2015). A theoretical and experimental study of atmospheric reactions of amines and their degradation products. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Amine-based CO2 capture has been proposed as a way of mitigating climate change. In this work, the fundamental processes governing the atmospheric gas phase chemistry of amines released from CO2 capture have been studiedusing computational and experimental methods. The reactions of amines, amides and imines with OH radicals have been studied with computational methods. The reactions are all characterized by strongly bound pre-reaction complexes and submerged barriers to hydrogen abstraction. Rate coefficients calculated from statistical rate theory show negative temperature dependencies and are in good agreement with experimental results where available. It has been suggested that the climate effect of amine based CO2 capture may be counteracted by the formation of N2O as a minor product in the photo-oxidation of methylamine. Calculations in this work unambiguously show that N2O is not a product in the photo-oxidation of methylamine. The reaction rate coefficients for the OH radical reactions of N-methylformamide and N,N-dimethylformamide have been measured as a function of temperature and pressure by using the flash photolysis laser-induced fluorescence technique. The reactions are significantly slower than the corresponding amine reactions and show a negative temperature dependence. The study further reveals that the amides have a higher potential for nitramine and nitrosamine formation and that they may therefore constitute a previously undisclosed health risk. Kinetic isotope effects for the OH radical reaction of HCN have been measured in a smog chamber through the use of FTIR spectroscopy. The measured values and calculated results confirm that the reaction, unlike the other reactions in this work, mainly occur through an addition channel. The present work has contributed significantly to our understanding of the atmospheric reactions of the intermediates in the atmospheric degradation of methyl amines.

• Maguta, Mihayo Musabila; Nielsen, Claus Jørgen; Myhre, Cathrine Lund & Stenstrøm, Yngve (2014). Environmental Impact of Amines emitted to the Atmosphere. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Industrial development, increase in population and need for improving the living standards of people around the globe have resulted into high demand of energy worldwide. The renewable energy sources seem to be unreliable and insufficient to meet this demand; hence the continued use of fossil fuels especially coal in power generation becomes necessary. Fossil fuels are well known for their environmental detriments including global warming which leads to climate change. With this cause, the world has to use the fossil fuels in an environmentally friendly manner to ensure that the amount of pollutants released into the atmosphere is minimized.<br> In combating climate change, technologies have been developed whereby the prime greenhouse gas, carbon dioxide is captured and stored. One of these technologies makes use of amines which at the end of the process are released into the atmosphere where they have been proven to undergo degradation leading to the formation of other several compounds including nitramines and nitrosamines, the latter being more potent carcinogenic.<br> In this study the loss pathways of four nitramines through their reaction with the well-known oxidants found in the atmosphere have been thoroughly investigated. Nitrosamines have been found to undergo rapid photolysis in the presence of sunlight, thus their reaction with the most abundant oxidant at night, the nitrate radical have been investigated using two simple nitrosamines.<br> The rate coefficients for OH radicals, Ozone and Cl atoms reactions with 4 nitramines at 298 K and 1013 hPa have been determined using relative rate method, and the lifetimes of the 4 nitramines following their reaction with these oxidants in the atmosphere have also been determined. Likewise, the rate coefficients for the reactions of the nitrate radicals (NO3) with two simple nitrosamines were determined at the same conditions using the same method. Moreover, the lifetimes of these nitrosamines following their reactions with the nitrate radicals in the atmosphere were calculated.<br> The primary products resulting from the reactions of OH radicals and Cl atoms with four nitramines have been investigated and hence identified using FT-IR detection method. Further, the OH initiated photooxidation of formamide have been studied as well and the only resulting product namely isocyanic acid was detected.<br> The Structure Activity Relationship (SAR) for OH reactions with nitramines was also studied and found not applicable due to the fact that, the reaction rate coefficients estimated using SAR differ significantly with the experimental results.<br> Infrared absorption cross-sections as well as integrated absorption intensities have been determined for a number of compounds.

• Nielsen, Claus Jørgen; D'Anna, Barbara; Bossi, Rossana; Bunkan, Arne Joakim Coldevin; Dithmer, Line & Glasius, Marianne [Vis alle 20 forfattere av denne artikkelen] (2012). Atmospheric Degradation of Amines (ADA) : summary report from atmospheric chemistry studies of amines, nitrosamines, nitramines and amides. Universitetet i Oslo. ISSN 9788299295475. doi: http:/hdl.handle.net/10852/12744. Fulltekst i vitenarkiv Vis sammendrag

  CLIMIT project no. 208122

• Mohr, Christian Wilhelm; Vogt, Rolf David; Nielsen, Claus Jørgen & Hessen, Dag Olav (2012). Preliminary assessment of the Fate of Nitramines in soil and freshwater - Executive Summary Report. Technology Centre Mongstad. Fulltekst i vitenarkiv
• Bråten, Hanne Birgitte; Bunkan, Arne Joakim Coldevin; Bache-Andreassen, Lihn; Sollimannejad, Mohammad & Nielsen, Claus Jørgen (2009). Final report on a theoretical study on the atmospheric degradation of selected amines. NILU. ISSN 9788242520463. Fulltekst i vitenarkiv Vis sammendrag

  Amines emitted into the atmosphere will undergo a series of chemical and physical processes. Compounds with liquid-phase vapour pressures > l0-6 Torr at the ambient atmospheric temperature will to a large extent undergo reactions in the gas phase. For the majority of gas-phase organic chemicals present in the troposphere, reaction with the OH radical is the dominant loss process. In general the degradation is initiated by reaction with OH and, where appropriate, direct photolysis and the reactions with O3 and NO3. In marine areas reactions with Cl atoms may also constitute an important sink. The types of radical generated following initiation processes include peroxy (RO2), oxy (RO) and excited and stabilized Criegee (R'R"COO) species, which each have a number of possible reactions which may be competitive under tropospheric conditions. The complex initiation and radical chemistry leads to the generation of many different products. Some are species which themselves have primary emissions, such as simple alcohols, aldehydes and ketones; others include complex (multifunctional) carbonyls, nitrates (RONO2), peroxy nitrates (RC(=O)OONO2), hydroperoxides (ROOH), percarboxylic acids (RC(=O)OOH) and carboxylic acids (RC(=O)OH). A literature survey was carried out and theoretical degradation mechanisms for selected amines have been developed on the basis of experimental findings.

• Gruber-Stadler, Margret; Nielsen, Claus Jørgen; Helgaker, Trygve & Mühlhäuser, Max (2008). Quantum chemistry studies of elementary atmospheric key reactions. Universitetet i Oslo. Fulltekst i vitenarkiv

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