INSITU SSIMS OBSERVATION OF CH BOND FORMATION ON A SPUTTERED NI(111) SURFACE

SSIMS, XPS and AES were used to observe the interaction of deuterium and hydrogen with carbidic carbon on a sputtered unannealed Ni(111) surface. The SSIMS measurements were performed in situ at an ambient H-2 (D2) pressure of 4 x 10(-6) Torr. The Ni2D+/Ni2+ signal was used to monitor the uptake of deuterium on the carbon saturated surface. A linear region with a sticking coefficient of the order of 10(-5) was observed for deuterium coverages up to approximately 0.1. The initial linear region is followed by a plateau and subsequent additional uptake. A comparison of SSIMS spectra taken during exposure of the carbidic carbon to H-2 with equivalent measurements using deuterium indicate the presence of CH2+, CH3+, Ni2CH+, NI2CH2+ and Ni2CH3+ secondary ions. XPS and AES measurements give supporting evidence for the formation of CH or CD bonds. Deuterium, in the presence or in the absence of ion irradiation, led to an increase in the C(1s) binding energy of approximately 0.25 eV. The AES C(KVV) feature also displayed changes in lineshape on exposure to deuterium. We conclude that CH, CH2 and CH3 and possibly some C2H(x) species are present on the surface during the in situ SSIMS analysis. We attribute the reactivity of the surface carbon to the fact that the experiments were performed on a high defect density surface.