IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM3
Morphology of Vapor-Deposited Ice at Low Temperatures by Atomic Force Microscopy

Tuesday, October 30, 2001, 9:00 am, Room 122

Session: Water at Surfaces
Presenter: S.C. Fain, University of Washington
Authors: S.C. Fain, University of Washington
J.M.K. Donev, University of Washington and Pacific Northwest National Laboratory
S.A. Joyce, Pacific Northwest National Laboratory
Correspondent: Click to Email
Atomic force microscopy (AFM) is being used to study the morphology of multilayer films of vapor-deposited water ice on various substrates as a function of deposition and annealing temperatures below 150K. These experimental studies are coordinated with theoretical studies by other investigators to provide improved understanding of ice growth and properties of ice for use in other fields. For example, nucleation and growth of crystalline ice particles in the upper atmosphere is of central importance for cloud formation, global energy balance, and dynamics of ozone depletion. For these experiments the films are deposited in-situ in ultra-high vacuum from an effusive doser at an angle of 67 degrees from the surface normal. The first measurements were made for ice films deposited on Au(111) on mica. These films were profiled by a probe tip attached to a quartz crystal (Omicron needle sensor) which provides nanometer resolution of surface features. Films deposited below 100K appear relatively flat, adopting the surface texture of the Au(111) substrate. Three-dimensional clusters typically 30 nm high form after annealing these films up to 130K. The lateral dimensions of the clusters depend on the initial coverage. These changes are produced by surface diffusion producing a non-wetting film. The rearrangement happened even if the annealing was done without imaging. Previous thermal desorption measurements by Kay and coworkers [J. Chem. Phys. 91, 5120-5121 (1989) and Surface Science 367, L13-L18 (1996)] have inferred amorphous ice clusters surrounded by bare substrate for films deposited on Au(111) at low-temperatures. Further measurements are in progress using non-contact AFM (Omicron beam-deflection) with the same deposition geometry and different substrates. Supported by Department of Energy's Office of Biological and Environmental Research, a U. W. Nanotechnology Fellowship Award to J.M.K.D., and NSF KDI 99-80125.