Chen L, Qiu S, Xiong F, Lu J, Liu P, Ding B, Li Y, Cui Y, Guo Y, Chen X. Nonadiabatic dynamics in energetic negative fluorine ions scattering from a Si(100) surface.
J Chem Phys 2015;
143:114703. [PMID:
26395724 DOI:
10.1063/1.4930908]
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Abstract
The dependence of the negative-ion fractions on incident energy and angle is reported for 8.5-22.5 keV F(-) ions scattered from a Si(100) surface at a fixed scattering angle of 38°. The negative-ion fraction increases monotonically with incident velocity for specular scattering. In particular, the variation of the fraction with incident angle is bell shaped for a given incident energy. We interpret this variation using the incident-velocity effect at short distances where the yield of negative ions depends on the number of initial neutrals. It strongly indicates that at short distances, a dynamical equilibrium population is never achieved. This nonadiabatic feature is supported by simple calculations using modified rate equations.
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