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Comparison of H2 Desorption Kinetics from Si(111)7×7 and Si(100)2×l

Published online by Cambridge University Press:  25 February 2011

M. L. Wise
Affiliation:
Dept. of Chemistry, Stanford University Stanford, Calif. 94305
B. G. Koehler
Affiliation:
Dept. of Chemistry, Stanford University Stanford, Calif. 94305
P. Gupta
Affiliation:
Dept. of Chemistry, Stanford University Stanford, Calif. 94305
P. A. Coon
Affiliation:
Dept. of Chemistry, Stanford University Stanford, Calif. 94305
S. M. George
Affiliation:
Dept. of Chemistry, Stanford University Stanford, Calif. 94305
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Abstract

The desorption kinetics of hydrogen from the β1 H2 -TPD state on Si(111)7×7 and Si(100)2×l were studied using laser-induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. Isothermal LITD studies of H2 desorption from Si(111)7×7 revealed second-order kinetics with a desorption activation energy of Ed = 62 ±4 kcal/mol and a preexponential factor of Vd = 92 ±10 cm2 /s. In contrast, H2 desorption from Si(100)2×l revealed first-order kinetics with an activation energy of Ed = 58 ±2 kcal/mol and a preexponential factor of Vd = 5.5 ±0.5 × 1015 s−1. The desorption kinetics yield similar upper limits for the Si-H bond energies but different desorption mechanisms on Si(lll)7×7 and Si(100)2×l.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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References

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