Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination
Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination
复制标题
自旋控制表面化学：通过非绝热氢消除从 Si(100)-2à1 中烷基解吸
DOI：
10.1039/d0cp01913e
复制
发表时间：
2020
影响因子：
3.3
通讯作者：
Casey, Sean M.
中科院分区：
文献类型：
--
作者：
Pohlman, Andrew J.;Kaliakin, Danil S.;Varganov, Sergey A.;Casey, Sean M.
对自旋态在半导体表面化学反应中所起作用的理解目前是有限的。在此，我们提供了非绝热反应的证据，涉及Si（100）表面二聚体悬空键的局部单线态到三重态热激发。通过将热解吸实验测得的乙基吸附物的β-氢消除动力学与电子结构计算结果进行比较，我们确定了其机理发生了依赖于覆盖的变化。在低覆盖下，非绝热的二聚体间机制占主导地位，而在高覆盖下，绝热机制占主导地位。计算结果表明，在室温附近，自旋交叉非常迅速，非绝热路径被一个比绝热路径小40 kJ mol−1的势垒加速。用非绝热过渡态理论（NA-TST）模拟了表面二聚体体系间交叉的热解吸反应，结果与实验结果吻合较好。
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.