TITLE:

Experimental verification of a new mechanism for dissociative chemisorption: atom abstraction

AUTHORS:

Li, Y.L.; Pullman, D.P.; Yang, J.J.; Tsekouras, A.A.; Gosalvez, D.B.; Laughlin, K.B.; Zhang, Z.; Schulberg, M.T.; Gladstone, D.J.; McGonigal, M.; Ceyer, S.T.; Dept. of Chem., MIT, Cambridge, MA, USA

PUBLICATION:

Physical Review Letters, vol.74, no.13, p. 2603-6, 27 March 1995 16 Refs.

ABSTRACT:

Abstraction of a F atom from incident F₂ by Si(100)-(2x1) is demonstrated by detection of the scattered, complementary F atom. He atom diffraction measurements are consistent with abstraction occurring at dangling bond sites. The low probability for single atom adsorption (P₁=0.10±0.01) relative to the total adsorption probability (P_t=0.96±0.02) in the zero coverage limit indicates that the second F atom can also be trapped by the dangling bonds. Both the single and two atom adsorption probabilities decay to zero when the dangling bonds are saturated at 1 ML coverage. Atom abstraction represents a mechanism distinct from the classic one for dissociative chemisorption.