The interface between benzenes (C6H6; C6H5Cl;2-C6H4OHCl) and amorphous solid water studied with metastable impact electron spectroscopy and ultraviolet photoelectron spectroscopy (HeI and II)

Interfaces between films of benzenes (C6H6;C6H5Cl;2-C6H4OHCl) and solid H2O on tungsten substrates were studied between 80 and 200 K with metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy [UPS(HeI and II)]. The following cases were studied in detail: (i) Adsorption of the benzenes on solid water in order to simulate their interaction with ice particles, and (ii) deposition of water on benzene films in order to simulate the process of water precipitation. In all cases the prepared interfacial layers were annealed up to 200 K under in situ control of MIES and UPS. The different behavior of the interfaces for the three studied cases is traced back to the different mobilities of the molecules with respect to that of water. The interaction between H2O and the benzenes at the interfaces is discussed on the basis of a qualitative profile for the free energy of that component of the interface which has the larger mobility. Possible implications of the present results for atmospheric physics are briefly mentioned. (C) 2004 American Institute of Physics.