Singh Vaibhav, Cheng Chuan, Weinacht Thomas, Matsika Spiridoula
Department of Chemistry, Temple University, Philadelphia, PA 19122, USA.
Department of Physics, Stony Brook University, Stony Brook, NY 11790, USA.
Phys Chem Chem Phys. 2022 Sep 14;24(35):20701-20708. doi: 10.1039/d2cp02604j.
Combined theoretical and experimental work examines the dynamics of dication formaldehyde produced by strong field ionization. Trajectory surface hopping dynamics on the first several singlet electronic states of the formaldehyde dication are used to examine the relaxation pathways and dissociation channels, while kinetic energy distributions after strong field ionization of formaldehyde and deuterated formaldehyde are used to confirm the theoretical predictions. We find that the first excited state of the formaldehyde dication is stable, neither decays to the ground state nor dissociates, even though the ground state and higher lying states are directly dissociative. The stability of the first excited state is explained by its symmetry which does not allow for radiative or nonradiative transitions to the ground state and by large barriers to dissociate on the excited state surface.
理论与实验相结合的工作研究了强场电离产生的双正离子甲醛的动力学。利用甲醛双正离子前几个单重电子态上的轨迹表面跳跃动力学来研究弛豫途径和解离通道，同时利用甲醛和氘代甲醛强场电离后的动能分布来证实理论预测。我们发现，甲醛双正离子的第一激发态是稳定的，既不衰减到基态也不解离，尽管基态和更高激发态是直接解离的。第一激发态的稳定性可通过其对称性来解释，该对称性不允许向基态进行辐射或非辐射跃迁，并且在激发态表面存在较大的解离势垒。
