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Photoexcitation Dynamics of Vibrationally Excited Molecules

振动激发分子的光激发动力学

基本信息

批准号：
09640613
负责人：
TSUCHIYA Soji
金额：
$ 1.86万
依托单位：
JAPAN WOMEN'S UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640613/
关键词：
Vibrational Dynamics Excited State 光解離反応

项目摘要

Excited state dynamics of rovibronically selected acetylene has been investigated by means of the laser-induced fluorescence(LIF) and the dispersed fluorescence(DF) spectroscopies.When acetylene in the electronic ground state(X^^-) is phtoexcited to levels in the electronic excited state(A^^-), most intense spectral transitions form a progression of trans-GH bending mode V^n(n=4-6). In the vicinity of the V^6 level in the A state, two near-lying levels were found to exist 4.5cm^<-1> apart. The DF spectra from these two levels were found to show signiicantly different spectral patterns : One DF spectrum is characterized by the trans-CH bending and CC stretching progressions, while the other one the cis-CH bending. This fact was interpreted as that the zero-order V^6 level interacts with a dark level including the cis-CH bending mode through anharmonic resonance, and thus, it is concluded that these two levels are located above the trans-cis isomerization barrier.The IR-UV double resonance spectroscopy was applied to observe the ungerade vibronic levels of acetylene in the A state to which one photon transition is forbidden from the vibronic ground level. The observed rotational line structure indicates a strong coupling between the cis in-plane CH bending(v^<S'>_6) and the out-of-plane CH bending(v^'_4) modes, though some unassignable lines remain to be discussed in terms of another type of interactions.

用激光诱导荧光(LIF)和色散荧光(DF)光谱研究了乙炔的激发态动力学.当电子基态(X^-)的乙炔被光激发到电子激发态(A^-)时，最强烈的光谱跃迁形成了反式生长激素弯曲模V^n(n=4-6)的级数.在A态的V^6能级附近，发现两个相邻能级相距4.5 cm^-1。这两个能级的DF谱表现出明显不同的光谱模式：一个DF谱表现为反式CH弯曲和CC伸缩过程，而另一个光谱表现为顺式CH弯曲过程。这一事实被解释为零级V^6能级通过非简谐共振与包括顺-CH弯曲模在内的暗能级相互作用，从而得出这两个能级位于反顺异构化势垒之上的结论。利用IR-UV双共振光谱观察了乙炔在A态下的未成熟振动能级，其中一个光子被禁止从振动基态跃迁到A态。观察到的旋转线结构表明，顺式面内CH弯曲(v^&lt；S‘&gt；_6)模与面外CH弯曲(v^’_4)模之间存在强耦合，但仍有一些不可指认的谱线有待从另一种相互作用的角度进行讨论。