Chen J M, Lu K T, Lee J M, Chen C K, Haw S C
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, Republic of China.
J Chem Phys. 2006 Dec 7;125(21):214303. doi: 10.1063/1.2400229.
The state-selective positive-ion and negative-ion dissociation pathways of gaseous and condensed Si(CH(3))(2)Cl(2) following Cl 2p, Cl 1s, and Si 2p core-level excitations have been characterized. The excitations to a specific antibonding state (15a(1) () state) of gaseous Si(CH(3))(2)Cl(2) at the Cl 2p, Cl 1s, and Si 2p edges produce significant enhancement of fragment ions. This ion enhancement at specific core-excited states correlates closely with the ion kinetic energy distribution. The results deduced from ion kinetic energy distribution are consistent with results of quantum-chemical calculations on Si(CH(3))(2)Cl(2) using the ADF package. The Cl(-) desorption yields for Si(CH(3))(2)Cl(2)Si(100) at approximately 90 K are notably enhanced at the 15a(1) () resonance at both Cl 2p and Si 2p edges. The resonant enhancement of Cl(-) yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide insight into the state-selective ionic fragmentation of molecules via core-level excitation.
气态和凝聚态的二氯二甲基硅烷（Si(CH(3))(2)Cl(2)）在Cl 2p、Cl 1s和Si 2p芯能级激发后的态选择性正离子和负离子解离途径已被表征。在Cl 2p、Cl 1s和Si 2p边缘处，气态Si(CH(3))(2)Cl(2)激发到特定反键态（15a(1)*态）会显著增强碎片离子。特定芯激发态下的这种离子增强与离子动能分布密切相关。从离子动能分布推导的结果与使用ADF软件包对Si(CH(3))(2)Cl(2)进行的量子化学计算结果一致。在约90 K时，Si(CH(3))(2)Cl(2)/Si(100)的Cl(-)解吸产率在Cl 2p和Si 2p边缘的15a(1)*共振处均显著增强。Cl(-)产率的共振增强是通过吸附分子形成高激发态而发生的。这些结果为通过芯能级激发实现分子的态选择性离子碎片化提供了深入了解。
