Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. I. Time-resolved photoelectron-photoion coincidence spectroscopy
Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. I. Time-resolved photoelectron-photoion coincidence spectroscopy
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DOI：
10.1063/1.5016452
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发表时间：
2018-04-28
影响因子：
4.4
通讯作者：
Stolow, Albert
中科院分区：
文献类型：
--
作者：
Boguslavskiy, Andrey E.;Schalk, Oliver;Stolow, Albert
用飞秒时间分辨光电子-光离子符合谱(TRPEPICO)研究了最小多烯反式-1，3-丁二烯的超快激发态动力学。激发态波包由216 nm处泵浦的明亮的B-1(U)(pi pi*)电子态产生，通过267 nm处的单光子和双光子电离投射到几个电离连续体上。结果用库普曼关联和涉及到的激发态和阳离子态的Frank-Condon因子来解释。利用已知的阳离子激发态的预解离特性，利用TRPEPICO光谱将光电子能带分配给特定的连续谱。这使得我们能够直接观察到反式1，3-丁二烯内转化过程中著名的难以捉摸的S-1(2(1)A(G))暗电子态。我们的唯象分析允许光谱测定几个重要的时间常数。我们报道了1(1)B(U)和2(1)A(G)态的总衰变寿命，并观察到热基态分子的重现。我们认为，导致吸收光谱极宽的S-2(11Bu)态的表观退相时间主要是由于B-1(U)表面上的大振幅扭转运动以及通过锥形交点的强非绝热耦合，从而使核波包恢复到初始的Franck-Condon区实际上是不可能的。见文件II[W.J.格洛弗等人，J.Chem.太棒了。148,164303(2018年)]，从头算多次产卵用于激发态非绝热波包动力学及其相关的TRPEPICO观测值的即时计算，允许直接将实验与理论进行比较。由AIP出版公司出版。
The ultrafast excited state dynamics of the smallest polyene, trans-1,3-butadiene, were studied by femtosecond time-resolved photoelectron-photoion coincidence (TRPEPICO) spectroscopy. The evolution of the excited state wavepacket, created by pumping the bright B-1(u) (pi pi*) electronic state at its origin of 216 nm, is projected via one-and two-photon ionization at 267 nm onto several ionization continua. The results are interpreted in terms of Koopmans' correlations and Franck-Condon factors for the excited and cationic states involved. The known predissociative character of the cation excited states is utilized to assign photoelectron bands to specific continua using TRPEPICO spectroscopy. This permits us to report the direct observation of the famously elusive S-1(2(1)A(g)) dark electronic state during the internal conversion of trans 1,3-butadiene. Our phenomenological analysis permits the spectroscopic determination of several important time constants. We report the overall decay lifetimes of the 1(1)B(u) and 2(1)A(g) states and observe the re-appearance of the hot ground state molecule. We argue that the apparent dephasing time of the S-2(11Bu) state, which leads to the extreme breadth of the absorption spectrum, is principally due to large amplitude torsional motion on the B-1(u) surface in conjunction with strong non-adiabatic couplings via conical intersections, whereupon nuclear wavepacket revivals to the initial Franck-Condon region become effectively impossible. In Paper II [W. J. Glover et al., J. Chem. Phys. 148, 164303 (2018)], ab initio multiple spawning is used for on-the-fly computations of the excited state non-adiabatic wavepacket dynamics and their associated TRPEPICO observables, allowing for direct comparisons of experiment with theory. Published by AIP Publishing.