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Imaging the Dissociation Dynamics of Si2+ via Two-Photon Excitation at 193 nm
Yu-jie Ma, Fang-fang Li, Jia-xing Liu, Feng-yan Wang*
Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, Shanghai 200433, China
Abstract:
In the one-color experiment at 193 nm, we studied the photodissociation of Si2+ ions prepared by two-photon ionization using the time-sliced ion velocity map imaging method. The Si+ imaging study shows that Si2+ dissociation results in two distinct channels: Si(3Pg)+Si+(2Pu) and Si(1D2)+Si+(2Pu). The main channel Si(3Pg)+Si+(2Pu)) is produced by the dissociation of the Si2+ ions in more than one energetically available excited electronic state, which are from the ionization of Si2(v=0-5). Particularly, the dissociation from the vibrationally excited Si2(v=1) shows the strongest signal. In contrast, the minor Si(1D2)+Si+(2Pu) channel is due to an avoided crossing between the two 22Πg states in the same symmetry. It has also been observed the one-photon dissociation of Si2+(X4Σg-) into Si(1D2)+Si+(2Pu) products with a large kinetic energy release.
Key words:  Slice imaging, Photodissociation, Silicon dimmer Si2, 193 nm
FundProject:
附件
在193 nm关于Si2分子的离子解离动力学的成像研究
马玉杰, 李芳芳, 刘嘉兴, 王凤燕*
复旦大学化学系,上海市分子催化和功能材料重点实验室,能源材料化学协同创新中心,上海 200438
摘要:
在193 nm的单色激光实验中,本文利用时间切片离子速度成像技术,研究了经193 nm双光子电离得到的Si2+的解离反应动力学过程. 根据实验得到的Si+离子的速度成像,观测到了两种离子直接解离通道:Si(3Pg)+Si+(2Pu)和Si(1D2)+Si+(2Pu). 电子基态的Si2分子处于v=0∽5的振动态上,其经过双光子电离后激发到Si2+离子的多个电子激发态势能面,生成主要通道Si(3Pg)+Si+(2Pu),其中v=1的解离信号最强. 此外,由于势能曲线22Πg与32Πg相同对称性引起的避免性势能面交叉,生成次要反应通道Si(1D2)+Si+(2Pu). 通道Si(1D2)+Si+(2Pu)的产物亦可以由生成的基态Si2+(X4Σg-)吸收一个193 nm光子后解离得到,其对应产物则具有更大的动能.
关键词:  切片成像,光解动力学,硅二聚体,193 nm
DOI:10.1063/1674-0068/cjcp1901011
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