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Issue 29, 2020
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Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination

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Abstract

An understanding of the role that spin states play in semiconductor surface chemical reactions is currently limited. Herein, we provide evidence of a nonadiabatic reaction involving a localized singlet to triplet thermal excitation of the Si(100) surface dimer dangling bond. By comparing the β-hydrogen elimination kinetics of ethyl adsorbates probed by thermal desorption experiments to electronic structure calculation results, we determined that a coverage-dependent change in mechanism occurs. At low coverage, a nonadiabatic, inter-dimer mechanism is dominant, while adiabatic mechanisms become dominant at higher coverage. Computational results indicate that the spin crossover is rapid near room temperature and the nonadiabatic path is accelerated by a barrier that is 40 kJ mol−1 less than the adiabatic path. Simulated thermal desorption reactions using nonadiabatic transition state theory (NA-TST) for the surface dimer intersystem crossing are in close agreement with experimental observations.

Graphical abstract: Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination

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Article information


Submitted
08 Apr 2020
Accepted
07 Jul 2020
First published
08 Jul 2020

Phys. Chem. Chem. Phys., 2020,22, 16641-16647
Article type
Paper

Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination

A. J. Pohlman, D. S. Kaliakin, S. A. Varganov and S. M. Casey, Phys. Chem. Chem. Phys., 2020, 22, 16641
DOI: 10.1039/D0CP01913E

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