IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM4
Study of CO@sub 2@ Adsorption on Ice using High-pressure X-ray Photoelectron-spectroscopy

Monday, October 29, 2001, 10:40 am, Room 120

Session: Aerosol and Related Chemistry
Presenter: F. Requejo, Lawrence Berkeley National Laboratory
Authors: F. Requejo, Lawrence Berkeley National Laboratory
H. Bluhm, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany
D.F. Ogletree, Lawrence Berkeley National Laboratory
M. Luna, Lawrence Berkeley National Laboratory
Z. Hussain, Lawrence Berkeley National Laboratory
C.S. Fadley, University of California, Davis
M. Salmeron, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
Water at surfaces plays a fundamental role in atmospheric science, chemistry and biology. A new generation of experimental and theoretical tools are actually revisited this subject.@footnote 1@ Many interesting properties of water still remain unexplained at molecular level, even though it has been a capital subject of research for decades. Interaction between ice surfaces and adsorbed molecules emerges as a very attractive topic. Macroscopic studies@footnote 2@ have investigated the adsorption of CO@sub 2@ on ice, showing the existence of a quasi-liquid layer on ice. On the other hand, new studies@footnote 3@ confirm that CO@sub 2@ is the main driver in global warming and glaciation changes. Recently, by means of surface X-ray absorption spectroscopy, we have studied the premelting of ice trough to the Auger electron yield NEXAFS from its surface. This methodology has proven to be capable of detecting and measuring the thickness of the liquid layer on ice. In the present contribution, we have applied the same methodology to study the effect of atmosphere CO@sub 2@ on the premelting of ice. Samples of ice and water were condensed from vapor onto a cooled substrate, which was placed inside a cell. In equilibrium conditions between the water vapor and the sample at different temperatures, CO@sub 2@ gas was introduced into the cell at different pressures in the range of 0 to 1 Torr. Afterwards, surface-sensitive XPS measurements and Auger electron-yield NEXAFS experiments at O K-edge in the energy range of 530 to 620 eV were performed. Our results indicate unambiguously that the amount of liquid water on the surface of ice increases with the pressure of CO@sub 2@. This effect becomes more evident when the temperature is also increased. @FootnoteText@ @footnote 1@ F. Bensebaa and T.H. Ellis. Progr. in Surf. Sc., 50, 1-4 (1995) 173. @footnote 2@ J. Ocampo and J. Klinger. J. Coll. Interf. Sci. 86, 2 (1982) 377. @footnote 3@ N.J. Shackleton. Science, 298 (2000) 1897. F.G. Requejo - Postdoctotoral Fellow at MSD, LBNL. Berkeley, CA. Permanent address: Dept. Physics, FCE, UNLP and IFILP(CONICET), La Plata, Argentina.