Geir Helgesen

Norwegian version of this page
Mobile phone 4539 3241
Username
Visiting address Gunnar Randers vei 19 None 2007 KJELLER
Postal address Postboks 70 2027 KJELLER
Other affiliations Department of physics

20% position at ITS.

 

Publications

  • Cernák, Jozef; Helgesen, Geir; Cizmar, Erik; Kovác, Jozef; Jurašeková, Zuzana & Voltr, Josef (2015). Magnetic properties of graphene nanodisk and nanocone powders at low temperatures. Physical Review B.  ISSN 2469-9969.  92 . doi: 10.1103/PhysRevB.92.155429
  • Knaapila, Matti; Høyer, Henrik & Helgesen, Geir (2015). Composite microdiscs with a magnetic belt: Preparation, chaining properties, and use as switchable catalyst carriers. ACS Applied Materials and Interfaces.  ISSN 1944-8244.  7(14), s 7795- 7800 . doi: 10.1021/acsami.5b01053
  • Sandsaunet, Marit Ulset; Knaapila, Matti; Tavares, Luciana; Kjelstrup-Hansen, Jacob & Helgesen, Geir (2015). Parallel integration of aligned carbon strings in polymer composite: Dielectrophoretic preparation, finite element simulation, and electrical characterization. Polymer Composites.  ISSN 0272-8397.  36(10), s 1866- 1874 . doi: 10.1002/pc.23094
  • Cernák, Jozef; Helgesen, Geir; Hage, Fredrik Sydow & Kovác, Jozef (2014). Magnetoresistance of composites based on graphitic discs and cones. Journal of Physics D: Applied Physics.  ISSN 0022-3727.  47(33) . doi: 10.1088/0022-3727/47/33/335305
  • Hage, Fredrik Sydow; Kepaptsoglou, Despoina Maria; Seabourne, Ché Royce; Ramasse, Quintim M.; Scott, Andrew J.; Prytz, Øystein; Gunnæs, Anette Eleonora & Helgesen, Geir (2014). Dielectric response of pentagonal defects in multilayer graphene nano-cones. Nanoscale.  ISSN 2040-3364.  6(3), s 1833- 1839 . doi: 10.1039/c3nr05419e
  • Knaapila, Matti; Høyer, Henrik & Helgesen, Geir (2014). Dielectrophoresis in particle confinement: Aligned carbon particles in polymer matrix below percolation threshold. The European Physical Journal Special Topics.  ISSN 1951-6355.  223(9), s 1869- 1882 . doi: 10.1140/epjst/e2014-02232-9
  • Knaapila, Matti; Høyer, Henrik; Kjelstrup-Hansen, Jacob & Helgesen, Geir (2014). Transparency enhancement for photoinitiated polymerization (UV curing) through magnetic field alignment in a piezoresistive metal/polymer composite. ACS Applied Materials and Interfaces.  ISSN 1944-8244.  6(5), s 3469- 3476 . doi: 10.1021/am405625z
  • Cernák, Jozef; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Kovác, Jozef; Voltr, Josef & Cizmar, Erik (2013). Magnetic properties of carbon nanodisk and nanocone powders. Physical Review B. Condensed Matter and Materials Physics.  ISSN 1098-0121.  87(1) . doi: 10.1103/PhysRevB.87.014434
  • Hage, Fredrik Sydow; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Prytz, Øystein; Gunnæs, Anette Eleonora; Helgesen, Geir & Brydson, Rik (2013). Topologically induced confinement of collective modes in multilayer graphene nanocones measured by momentum-resolved STEM-VEELS. Physical Review B. Condensed Matter and Materials Physics.  ISSN 1098-0121.  88(15) . doi: 10.1103/PhysRevB.88.155408
  • Mauroy, Henrik; Plivelic, Tomás S.; Hansen, Elisabeth Lindbo; Fossum, Jon Otto; Helgesen, Geir & Knudsen, Kenneth (2013). Effect of clay surface charge on the emerging properties of polystyrene-organoclay nanocomposites. Journal of Physical Chemistry C.  ISSN 1932-7447.  117(38), s 19656- 19663 . doi: 10.1021/jp403379h Full text in Research Archive
  • Mauroy, Henrik; Rozynek, Zbigniew; Plivelic, Tomás S.; Fossum, Jon Otto; Helgesen, Geir & Knudsen, Kenneth (2013). Oxygen-Controlled Phase Segregation in Poly(N-isopropylacrylamide)/Laponite Nanocomposite Hydrogels. Langmuir.  ISSN 0743-7463.  29(1), s 371- 379 . doi: 10.1021/la303889s Full text in Research Archive
  • Helgesen, Geir; Knaapila, Matti; Skjeltorp, Arne Torbjørn; Høyer, Henrik & Cernak, J (2012). Field induced microparticle structure formation in fluids . Revista Cubana de Física.  ISSN 0253-9268.  29(1E34)
  • Høyer, Henrik; Knaapila, Matti; Kjelstrup-Hansen, Jacob & Helgesen, Geir (2012). Microelectromechanical strain and pressure sensors based on electric field aligned carbon cone and carbon black particles in a silicone elastomer matrix. Journal of Applied Physics.  ISSN 0021-8979.  112(9) . doi: 10.1063/1.4759447
  • Høyer, Henrik; Knaapila, Matti; Kjelstrup-Hansen, Jacob; Liu, Xuhai & Helgesen, Geir (2012). Individual strings of conducting carbon cones and discs in a polymer matrix: Electric field-induced alignment and their use as a strain sensor. Journal of Polymer Science Part B: Polymer Physics.  ISSN 0887-6266.  50(7), s 477- 483 . doi: 10.1002/polb.23031
  • Johnsen, Gorm Krogh; Knaapila, Matti; Martinsen, Ørjan Grøttem & Helgesen, Geir (2012). Conductivity enhancement of silver filled polymer composites through electric field alignment. Composites Science And Technology.  ISSN 0266-3538.  72(15), s 1841- 1847 . doi: 10.1016/j.compscitech.2012.07.011
  • Lukin, A.A.; Il'yashenko, E. I.; Skjeltorp, Arne Torbjørn & Helgesen, Geir (2012). Improvement of thermal stability of Nd-Tb-Fe-Co-B sintered magnets by additions of Pr, Ho, Al, and Cu. Physics Research International.  ISSN 2090-2220. . doi: 10.1155/2012/416717
  • Sobas, Pawel Andrzej; Knudsen, Kenneth Dahl; Helgesen, Geir; Skjeltorp, Arne T. & Fossum, Jon Otto (2012). CO2 and porous media – SANS, In Jon Otto Fossum & Giovani Vasconcelos (ed.),  Proceedings of the 2nd International Workshop on Complex Physical Phenomena in Materials : Hotel Armação, Porto de Galinhas - PE, Brazil, January 31-February 3, 2012.  Complexphysics.org.  ISBN 978-82-93224-06-8.  Article pages 49-50.  s 49 - 50
  • Høyer, Henrik; Knaapila, Matti; Kjelstrup-Hansen, Jacob; Liu, Xuhai & Helgesen, Geir (2011). A strain sensor based on an aligned carbon particle string in a UV-cured polymer matrix. Applied Physics Letters.  ISSN 0003-6951.  99(21) . doi: 10.1063/1.3662969
  • Knaapila, M.; Høyer, Henrik; Svåsand, Eldrid; Buchanan, Mark; Skjeltorp, Arne Torbjørn & Helgesen, Geir (2011). Aligned Carbon Cones in Free-Standing UV-Curable Polymer Composite. Journal of Polymer Science Part B: Polymer Physics.  ISSN 0887-6266.  49(6), s 399- 403 . doi: 10.1002/polb.22198
  • Knaapila, Matti; Pinheiro, Jean Patrick; Buchanan, Mark; Skjeltorp, Arne Torbjørn & Helgesen, Geir (2011). Directed assembly of carbon nanocones into wires with an epoxy coating in thin films by a combination of electric field alignment and subsequent pyrolysis. Carbon.  ISSN 0008-6223.  49(10), s 3171- 3178 . doi: 10.1016/j.carbon.2011.03.039
  • Knaapila, Matti; Svåsand, Eldrid; Pinheiro, Jean Patrick; Martinsen, Ørjan Grøttem; Buchanan, Mark; Skjeltorp, Arne Torbjørn; Helgesen, Geir & Rømoen, Ola Taarud (2011). Conductivity Enhancement in Carbon Nanocone Adhesive by Electric Field Induced Formation of Aligned Assemblies. ACS Applied Materials and Interfaces.  ISSN 1944-8244.  3(2), s 378- 384 . doi: 10.1021/am100990c
  • Holt, Arve; Thøgersen, Annett; Rohr, Carsten; Bye, Jan-Inge; Helgesen, Geir; Nordseth, Ørnulf; Jensen, Sten Aksel; Norheim, Lasse & Nielsen, Øyvind (2010). Surface structure of mono-crystalline silicon wafers produced by diamond wire sawing and by standard slurry sawing before and after etching in alkaline solutions, In IEEE IEEE (ed.),  35th IEEE Photovoltaic Specialists Conference Honolulu, HI June 20-25, 2010.  IEEE Press.  ISBN 978-1-4244-5891-2.  x.  s 3501 - 3504
  • Paula, F.L.O.; Da Silva, G.J.; Aquino, R.; Depeyrot, J.; Fossum, Jon Otto; Knudsen, Kenneth D; Helgesen, Geir & Tourinho, F.A. (2009). Gravitational and magnetic separation in self-assembled clay-ferrofluid nanocomposites. Brazilian journal of physics.  ISSN 0103-9733.  39, s 163- 170 . doi: 10.1590/S0103-97332009000200007
  • Naess, S.N.; Elgsaeter, A.; Helgesen, Geir & Knudsen, K.D. (2009). Carbon nanocones: Wall structure and morphology. Science and Technology of Advanced Materials.  ISSN 1468-6996.  10 . doi: 10.1088/1468-6996/10/6/065002
  • Svåsand, Eldrid; Kristiansen, Kai de Lange; Martinsen, Ørjan Grøttem; Helgesen, Geir; Grimnes, Sverre & Skjeltorp, Arne Torbjørn (2009). Behavior of carbon cone particle dispersions in electric and magnetic fields. Colloids and Surfaces A: Physicochemical and Engineering Aspects.  ISSN 0927-7757.  339(1-3), s 211- 216 . doi: 10.1016/j.colsurfa.2009.02.025

View all works in Cristin

  • Cavalcanti, Leide Passos; Kalantzopoulos, Georgios N.; Sobas, Pawel Andrzej; Bordallo, Heloisa N.; Helgesen, Geir; Knudsen, Kenneth & Fossum, Jon Otto (2017). High charge density smectite clays for CO2 capture, Leide P. Cavalcanti, Georgios Kalantzopoulos, Pawel Sobas, Heloisa N. Bordallo, Geir Helgesen, Kenneth D Knudsen and Jon Otto Fossum, talk presented at 16th International Clay Conference (16ICC): Clays from the Oceans to Space, in Session ES02: Environmental Applications of Clay Minerals, Granada Spain July 17th 2017.
  • Cavalcanti, Leide Passos; Kalantzopoulos, Georgios N.; Sobas, Pawel Andrzej; Bordallo, Heloisa N.; Helgesen, Geir; Knudsen, Kenneth & Fossum, Jon Otto (2017). Why are high charge density clays effective for CO2 capture?, L. P. Cavalcanti, G. Kalantzopoulos, P. Sobas, H. N. Bordallo, G. Helgesen, K. D. Knudsen, J. O. Fossum, Norsk Fysisk Selskap - Fysikermøtet 2017, Tromsø Aug 7-9 2017.
  • Skjeltorp, Arne Torbjørn & Helgesen, Geir (2016). Editorial. The European Physical Journal Special Topics.  ISSN 1951-6355.  225(4), s 627- 628 . doi: 10.1140/epjst/e2016-60134-1
  • Michels, Leander; Fossum, Jon Otto; Rozynek, Zbigniew Jerzy; Hemmen, Henrik; Rustenberg, Karin Hveding; Sobas, Pawel Andrzej; Kalantzopoulos, Georgios N.; Helgesen, Geir; Knudsen, Kenneth Dahl; Janek, Márian; Plivelic, Tomás S. & da silva, Geraldo Jose (2015). Intercalation and Retention of Carbon Dioxide in a Smectite Clay promoted by Interlayer Cations.
  • Skjeltorp, Arne Torbjørn & Helgesen, Geir (2014). Editorial. The European Physical Journal Special Topics.  ISSN 1951-6355.  223(9), s 1743- 1744 . doi: 10.1140/epjst/e2014-02222-y
  • Mauroy, Henrik; Hansen, Elisabeth Lindbo; Rozynek, Zbigniew; Plivelic, Tomás S.; Fossum, Jon Otto; Helgesen, Geir & Knudsen, Kenneth (2013). Polystyrene‐clay nanocomposites: the effect of clay surface charge.
  • Mauroy, Henrik; Rozynek, Zbigniew; Plivelic, Tomás S.; Fossum, Jon Otto; Helgesen, Geir & Knudsen, Kenneth (2013). Phase segregation in PNIPAAM‐laponite hydrogels: the effect of dissolved oxygen.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Mauroy, Henrik & Fossum, Jon Otto (2013). Supercritical CO2 in aerogels and clay materials studied by small angle neutron scattering.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Mauroy, Henrik & Fossum, Jon Otto (2013). Supercritical CO2 in aerogels and clay materials studied by small angle neutron scattering.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Mauroy, Henrik; Kalantzopoulos, Georgios N. & Fossum, Jon Otto (2013). CO2 adsorption and intercalation in aerogels and clay materials studied by SANS.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Måløy, Knut Jørgen; Rozynek, Zbigniew & Fossum, Jon Otto (2013). Dynamic Light Scattering measurements of clay materials in lquid CO2: Preliminary results.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Måløy, Knut Jørgen; Rozynek, Zbigniew & Fossum, Jon Otto (2013). Dynamic light scattering measurements of clay materials in liquid CO2: preliminary results.
  • Mauroy, Henrik; Knudsen, Kenneth Dahl; Helgesen, Geir; Fossum, Jon Otto & Rozynek, Zbigniew (2012). Synthesis and Characterization of Polysterene-Clay nanocomposites, 2nd International Workshop on Complex Physical Phenomena in Materials, Porto de Galinhas – PE, Brazil, Jan. 31 – Feb. 3, 2012.
  • Skjeltorp, Arild Terje & Helgesen, Geir (2012). Cooperative phenomena in flows: multidisciplinary perspectives. The European Physical Journal Special Topics.  ISSN 1951-6355.  204(1), s 1- 3 . doi: 10.1140/epjst/e2012-01547-9
  • Sobas, Pawel Andrzej; Knudsen, Kenneth Dahl; Helgesen, Geir; Skjeltorp, Arne T. & Fossum, Jon Otto (2012). CO2 and porous media - SANS, 2nd International Workshop on Complex Physical Phenomena in Materials, Porto de Galinhas – PE, Brazil, Jan. 31 – Feb. 3, 2012.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth Dahl; Helgesen, Geir; Skjeltorp, Arne T.; Måløy, Knut Jørgen & Fossum, Jon Otto (2012). Electric field alignement of clay particles, International Workshop on Soft Matter Physics & Complex Flows, Lofoten, Norway, May 22-25, 2012.
  • Sobas, Pawel Andrzej; Knudsen, Kenneth; Helgesen, Geir; Skjeltorp, Arne Torbjørn; Måløy, Knut Jørgen & Fossum, Jon Otto (2012). Dynamic Light Scattering measurements of clay materials in liquid CO2: Preliminary results.
  • Hage, Fredrik Sydow; Helgesen, Geir; Gunnæs, Anette Eleonora & Prytz, Øystein (2010). Graphitization of carbon nanocones and nanodiscs.
  • Helgesen, Geir; Knudsen, K.D.; Skjeltorp, Arne Torbjørn; Cuesta, H.F.; Elgsæter, A.; Garberg, T.; Næss, S.N. & Knaapila, M. (2009). The Structure of Carbon Cones and Disks.
  • Helgesen, Geir; Knudsen, K.D.; Skjeltorp, Arne Torbjørn; Knaapila, M.; Pinheiro, J.P.; Bourgeaux, M.; Heiberg-Andersen, H.; Gunnæs, Anette Eleonora & Prytz, Øystein (2009). The structure and properties of carbon cones.
  • Gunnæs, Anette Eleonora; Prytz, Øystein; Olsen, Arne; Helgesen, Geir & Knudsen, K. D. (2009). Structural study of C-cones and discs by use of analytical TEM.
  • Helgesen, Geir (2009). Structure of carbon cones.
  • Svåsand, Eldrid; Helgesen, Geir & Skjeltorp, Arne Torbjørn (2009). Karbonkjegler og magisk væsker. Fra Fysikkens Verden.  ISSN 0015-9247.  71(2), s 52- 56
  • Meheust, Yves; Fossum, Jon Otto; Knudsen, Kenneth Dahl; Maloy, Knut Jorgen & Helgesen, Geir (2008). Mesoscopic changes of a model clay soil due to the microscopic swelling of its crystallites.
  • Meheust, Yves; Fossum, Jon Otto; Knudsen, Kenneth Dahl; Pamar, K.P.S; Måløy, Knut Jørgen & Helgesen, Geir (2008). Utilizing WAXS to characterize the orientation distribution of clay assemblies – application to electro-rheological suspensions and weakly-hydrated samples.
  • Knudsen, Kenneth; Fossum, Jon Otto; Helgesen, Geir; Bergaplass, Vegard & Haakestad, Magnus Willum (2004). Pore characteristics and pressure effects in a nano-layered silicate.
  • Knudsen, Kenneth; Fossum, Jon Otto; Helgesen, Geir & Haakestad, Magnus Willum (2002). Pore characteristics and water absorption in a synthetic smectite clay.
  • Haakestad, Magnus Willum; Aalerud, Tommy Nakken; Lutnæs, Simen Berg; Fossum, Jon Otto; Helgesen, Geir & Knudsen, Kenneth (2001). Small-angle neutron scattering studies of a synthetic clay: Sodium fluorohectorite.

View all works in Cristin

Published Jan. 17, 2017 3:34 PM - Last modified June 28, 2017 2:52 PM