Adsorption of fluorine on bare, hydrogen- and hydrocarbon-covered diamond C(111) surfaces

The adsorption of fluorine delivered as xenon difluoride has been examined on a bare diamond C(111)(2 x 1) surface as well as modified surfaces of hydrogen-terminated H:C(111)(1 x 1) and hydrocarbon-precovered CH3/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 x 1) at nearly 10(5) 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 x 1) was one monolayer. The adsorbed F on H:C(III)(I x 1) was removed by annealing to 1300 K and H:C(111)(1 x 1) was restored. On C(111) precovered with CH3 groups, the initial sticking probability of F was definitely smaller than that of C(1 1 1)(2 x 1). The adsorbed F was less stable and desorbed completely at 1200 K. The structures of adsorbed F on C(111)(2 x 1) and H:C(111)(1 x 1) are discussed.