School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala P.O, Vithura, Thiruvananthapuram-695551, Kerala, India.
Department Of Chemistry, School Of Physical Sciences, Central University of Kerala, Tejaswini Hills, Periya, Kerala - 671320, India.
Phys Chem Chem Phys. 2020 Apr 29;22(16):8745-8756. doi: 10.1039/d0cp00741b.
A theoretical study is used to explore the involvement of O-H vibrational motions in the S0 → S2 photoinduced dynamics of 3-hydroxypyran-4-one (3-HOX). Two transitions, S0 → S1 and S0 → S2, are attributed to the experimentally observed electronic absorption spectral features in the range of 3.5-5.5 eV. We compute model potential energy surfaces of vibronically coupled S1 (nπ*) and S2 (ππ*) states with the aid of extensive electronic structure calculations. The S1-S2 conical intersection is characterized in the O-H bend and O-H stretch vibrational coordinate space. Quantum wavepacket dynamics simulations reveal an ultrafast S2 → S1 internal conversion decay, where about 90% of the S2 population disappears within the first 50 fs of the propagation time. The participation of O-H vibrational motions in the early events of nonadiabatic dynamics is analyzed based on the time evolution of nuclear densities on S2. We discuss the implications of these observations to provide fundamental insights into the nonadiabatic excited-state intramolecular proton transfer in 3-HOX and its derivatives.
本文通过理论研究探讨了 O-H 振动运动在 3-羟基-4-吡喃酮（3-HOX）的 S0→S2 光致动力学中的作用。S0→S1 和 S0→S2 两个跃迁归因于实验观测到的在 3.5-5.5 eV 范围内的电子吸收光谱特征。我们借助广泛的电子结构计算，计算了 Vibronically 耦合的 S1（nπ*）和 S2（ππ*）态的模型势能面。在 O-H 弯曲和 O-H 伸缩振动坐标空间中，S1-S2 交叉锥被特征化。量子波包动力学模拟揭示了超快的 S2→S1 内转换衰减，其中在传播时间的前 50 fs 内，约 90%的 S2 种群消失。基于 S2 上核密度的时间演化，分析了 O-H 振动运动在非绝热动力学早期事件中的参与情况。我们讨论了这些观察结果的意义，为 3-HOX 及其衍生物的非绝热激发态分子内质子转移提供了基本的见解。
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