Cryogenic stabilization of high vapor pressure samples for surface analysis under ultrahigh vacuum conditions

A novel form of ultrahigh vacuum (UHV) cryogenic stabilization has been use d to obtain high-resolution x-ray photoelectron - spectroscopy (XPS) data f rom a complex amine, 1,8-bis(dimethylamino) naphthalene, whose solid phase exhibited at room temperature an unacceptably high rate of sublimation. Pro tonated versions of the amine exhibit hydrogen bonding. Electron spectrosco py for chemical analysis chemical shifts can be used to describe the streng th and asymmetry of hydrogen bonding formed in proton sponge complexes. Ana lyzing the binding energy shifts of N (1s) induced by the presence of this hydrogen bonding required obtaining corresponding XPS spectra from the nonp rotonated (reference) sample, but the reference sample sublimes under even moderate vacuum conditions. The combined results suggest that other high va por pressure materials, particularly those that were previously considered to be too corrosive for routine analysis, can be cryogenically stabilized f or surface analysis under similar UHV conditions. (C) 1999 American Vacuum Society. [S0734-2101(99)09605-0].