碳在钼(100)和钼(111)表面上的超结构

用一定能量的氩离子束轰击含碳、氧的钼(100)和(111)表面,不能除去表面上的碳。而用能量为1千电子伏,束流为6微安的氮离子轰击10—15分钟,氮在表面的吸附达到饱和值。加热到400—600℃之间碳、氧从表面上基本消失,600—650℃之间吸附在表面上的氮大量脱附,即氮峰陡降到较低值,碳又偏析到表面上。加热到730℃和775℃氮从表面消失,分别得到碳在钼(100)表面上的p(2×2)和c(6×2)结构。而若将大量脱附氮的钼(111)表面,冷却到室温,氧又偏析到表面上。重新加热到650℃以上碳先从表面消失 关键词：

SUPERSTRUCTURE FORMED BY SEGREGATION OF CARBON ON Mo(100) AND Mo(111) SURFACES

Carbon and oxygen on the Mo(l00) and Mo(l1l) surfaces can not be removed by bombarding the sample with argon ions at the ambient temperature. While carbon and oxygen can be reduced by bombarding the sample using nitrogen ions with primary energy of 1 keV and beam current of 6 μA for 10-15 min. This may be due to the adsorption of nitrogen reached saturation. After heating sample to 400-600℃ carbon and oxygen disappeared; at 600-650℃, Auger peak of nitrogen dropped suddenly and then decreased gradually with increasing temperature, carbon segregated simultaneously on the surface. Complete desorption of nitrogen took place at 730℃ and 775℃, A p(2×2)-C and a c(6×2)-C LEED patterns were observed respectively. After nitrogen desorbtion, the sample is cooled to room temperature, oxygen segregated on Mo(lll) surface. Repeated heating to above 650℃, carbon disappeared from the surface, nitrogen and oxygen appeared on the surface, until at 800℃ nitrogen and oxygen disappeared completely and a clean surface Mo(lll) LEED pattern was obtained. Then cooling the sample to room temperature, oxygen segregated on surface again. After bombarding the Mo(lll) surface with argon ions, carbon and nitrogen agan appeared on the surface. Heating to 700℃ and 760℃ oxygen and nitrogen disappeared and a p(6×6)-C LEED pattern was obtained.