Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study.
Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study.
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DOI：
10.1063/1.4938423
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Guorong Wu;S. Neville;O. Schalk;T. Sekikawa;M. Ashfold;G. Worth;A. Stolow
中科院分区：
文献类型：
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作者：
Guorong Wu;S. Neville;O. Schalk;T. Sekikawa;M. Ashfold;G. Worth;A. Stolow
采用时间分辨光电子能谱（TRPES）、多层多构型时间依赖Hartree方法从头算量子动力学计算以及高能级光电离截面计算相结合的方法研究了n -甲基吡咯在241.5 ~ 217.0 nm波长激发后的动力学。在241.5 nm和236.2 nm激发得到A2（πσ(∗)）态的居族，与先前的研究一致。在217.0 nm处激发形成先前被忽略的B1（π3py）里德堡态，随后迅速内部转换为A2（πσ(∗)）态。与吡罗的光致动力学相反，发现波包在A2（πσ(∗)）态的寿命随激发波长的变化而变化，从241.5 nm调谐到236.2 nm时减少了一个数量级，在217.0 nm激发时减少了三个数量级以上。在较长激发波长下测量到的寿命的数量级差异归因于A2（πσ(∗)）态的振动激发，促进了波包在N-CH3解离坐标中围绕势垒的运动。
The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A2(πσ(∗)) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B1(π3py) Rydberg state, followed by prompt internal conversion to the A2(πσ(∗)) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A2(πσ(∗)) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A2(πσ(∗)) state, facilitating wavepacket motion around the potential barrier in the N-CH3 dissociation coordinate.