Studies of Physical Adsorption

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A new Materials research Group is established to investigate fundamental aspects of physical adsorption and phase transitions in physisorbed films. The goals of the research are to study both the structure and kinetics of physisorbed films, and the nature of these phases and the transitions between them. The research is organized into five topics: (1) melting of monolayer argon films on graphite, (2) phase transitions of films of binary adsorbates, (3) properties of simple gases in a well- characterized zeolite porous medium, (4) unusual properties of monolayer and multilayer helium films on weak-binding substrates, (5) desorption and helium atom scattering of films. Experimental efforts include measurement of heat capacity, in-situ vapor pressure isotherm study, inelastic helium scattering, high- resolution low-energy electron diffraction, inelastic helium scattering, neutron scattering, time-of-flight desorption measurements, and wetting and superfluid studies. Molecular dynamics computer simulation is being used to provide realistic modelling of adsorbate behavior and phase transitions of thin films and confined fluids. Interaction potentials, atom-surface scattering, and classical and quantum transitions of adsorbate systems are being studied in the theoretical thrusts of the program using potential energy models and statistical mechanics approaches. The strong coupling of experiment, computational simulation and theory are making advances not possible by isolated approaches.