Adsorption of Fluorine on Bare, Hydrogen- and Hydrocarbon-Covered Diamond C(111) Surfaces

Abstract

The adsorption of fluorine delivered as xenon difluoride has been examined on a bare diamond C(111)(2×1) surface as well as modified surfaces of hydrogen-terminated H:C(111)(1×1) and hydrocarbon-precovered CHx/C(111) by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED). The F intake by bare C(111)(2×1) at nearly 105 Langmuir of XeF2 exposure reached close to two monolayers on C(111). The adsorbed F was removed by annealing to 1400 K in vacuum, and was replaced by atomic hydrogen generated by a hot filament. The saturation coverage of F on H:C(111)(1×1) was one monolayer. The adsorbed F on H:C(111)(1×1) was removed by annealing to 1300 K and H:C(111)(1×1) was restored. On C(111) precovered with CHx groups, the initial sticking probability of F was definitely smaller than that of C(111)(2×1). The adsorbed F was less stable and desorbed completely at 1200 K. The structures of adsorbed F on C(111)(2×1) and H:C(111)(1×1) are discussed.