Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination
| Autor: | Sean M. Casey, Andrew J Pohlman, Danil S. Kaliakin, Sergey A. Varganov |
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| Rok vydání: | 2020 |
| Předmět: |
Spin states
Chemistry Dangling bond Thermal desorption General Physics and Astronomy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Transition state theory Intersystem crossing Chemical physics Spin crossover Desorption Singlet state Physics::Chemical Physics Physical and Theoretical Chemistry 0210 nano-technology |
| Zdroj: | Physical Chemistry Chemical Physics. 22:16641-16647 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/d0cp01913e |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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