State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China; Graduate School of the Chinese Academy of Sciences, Beijing, PR China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jan 5;224:117466. doi: 10.1016/j.saa.2019.117466. Epub 2019 Aug 10.
Femtosecond time-resolved transient absorption spectroscopy is employed to investigate the ultrafast excited-state dynamics from the S state of dibenzofuran and the hydrogen bonding effect in protic and aprotic solvents. Following the excitation with 266 nm, the initial population on the S state couples to the S state via internal conversion on tens of picoseconds. Afterwards, vibrational energy relaxation (VER) with dozens of picoseconds is determined in all solvents and strongly depended on the polarities of aprotic solvents. And the rising species related with the hydrogen-bonded intermediate S state are observed just in ethanol and methanol with the higher Kamlet parameter α. Subsequently, the intersystem crossing from the S state to the triplet manifold is a main deactivation pathway with the decay time of ≫ns. All the relaxation processes exhibit solvent dependence, indicating that hydrogen bonding interaction between solute and solvent enhances VER and significantly influences on the excited state dynamics of dibenzofuran.
飞秒时间分辨瞬态吸收光谱用于研究二苯并呋喃 S 态的超快激发态动力学以及质子性和非质子性溶剂中的氢键效应。用 266nm 激发后，S 态上的初始布居通过数十皮秒的内转换与 S 态耦合。随后，在所有溶剂中均确定了数十皮秒的振动能量弛豫（VER），并且 VER 强烈依赖于非质子性溶剂的极性。并且仅在乙醇和甲醇中观察到与氢键中间 S 态有关的上升物种，这与较高的 Kamlet 参数α有关。随后，S 态到三重态的系间窜越是主要的失活途径，衰减时间为≫ns。所有的弛豫过程都表现出溶剂依赖性，表明溶质和溶剂之间的氢键相互作用增强了 VER，并对二苯并呋喃的激发态动力学有显著影响。
