State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, PR China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, PR China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, PR China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jun 5;274:121065. doi: 10.1016/j.saa.2022.121065. Epub 2022 Feb 26.
Femtosecond time-resolved photoelectron spectroscopy was employed to investigate the ultrafast non-adiabatic dynamics of diethylamine (DEA). Following the direct excitations of the two main conformational structures (i.e., TT and TG) of DEA to the 3p Rydberg states at 200 nm, DEA undergoes internal conversion to the 3s state with ∼68 fs, which is similar to previously relaxation pathways of several secondary and tertiary amines. Subsequent dynamics on the 3s Rydberg state evolves along the NH stretching coordinate and is then accompanied by the breaking of the NH bond in about 120 fs, rather than the cleavage of the NC, or CC bonds as well as the conformational transformations between the TT and TG conformers on the 3s states. Theoretically, we reveal the pre-dissociative nσ* character evolving along the NH stretching coordinate within the 3s state as DEA dissociates to yield H atom products. As contrasted to the well-known conformational NC bond rotation motions in systems such as tertiary amines, the non-adiabatic relaxation of the 3s state of DEA is predominantly characterized by the NH bond dissociation process.
飞秒时间分辨光电子能谱被用来研究二乙胺（DEA）的超快非绝热动力学。在 200nm 处直接激发 DEA 的两种主要构象结构（即 TT 和 TG）到 3p 里德堡态后，DEA 以 ∼68fs 的速度经历内转换到 3s 态，这与之前几种仲胺和叔胺的弛豫途径相似。随后在 3s 里德堡态上的动力学沿着 NH 伸缩坐标演化，然后在大约 120fs 内伴随着 NH 键的断裂，而不是 NC 或 CC 键的断裂，以及在 3s 态下 TT 和 TG 构象之间的构象转变。从理论上揭示了在 3s 态中沿着 NH 伸缩坐标演化的预解离 nσ*特征，因为 DEA 解离生成 H 原子产物。与三级胺等系统中众所周知的构象 NC 键旋转运动相反，DEA 的 3s 态的非绝热弛豫主要由 NH 键的解离过程来描述。
