超快强场相干调控氯溴甲烷分子的解离研究  

Dissociation of chlorobromomethane molecules coherently controlled by ultrafast strong field

作　　者：景文泉 贾利娟 孙兆鹏 赵松峰 束传存 Jing Wen-Quan;Jia Li-Juan;Sun Zhao-Peng;Zhao Song-Feng;Shu Chuan-Cun(Hunan Key Laboratory of Super Microstructure and Ultrafast Process,School of Physics,Central South University,Changsha 410083,China;Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China;Institute of Theoretical Physics,School of Physics and Optoelectric Engineering,Ludong University,Yantai 264025,China)

机构地区：[1]中南大学物理学院,湖南省超微结构与超快过程重点实验室,长沙410083 [2]西北师范大学物理与电子工程学院,甘肃省原子分子物理与功能材料重点实验室,兰州730070 [3]鲁东大学物理与光电工程学院,理论物理研究所,烟台264025

出　　处：《物理学报》2024年第24期77-90,共14页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2022YFA1604204);国家自然科学基金(批准号:12164044,12274470,61973317);湖南省杰出青年自然科学基金(批准号:2022JJ10070)资助的课题.

摘　　要：超快强场相干调控分子解离在原子与分子物理、物理化学、量子调控等多个领域引起了重要关注,在现象理解、机理探究和调控方案等多个方面仍然存在许多值得深入研究的问题.近期研究表明,在保持光谱振幅分布不变的条件下,对最初处于基电子态纯本征态的分子,通过调制单个超快强紫外激光脉冲的光谱相位分布,可以有效调控总解离概率和分支比.本文采用含时量子波包方法,进一步探讨了光谱相位调控氯溴甲烷(CH_(2)BrCl)分子的光解离反应,着重探究了初始振动态对解离反应的影响.为了凸显超快强场脉冲调控解离机理与弱场的不同,本文展示了在弱场极限下,改变单个超快脉冲的谱相位不会影响总解离概率和分支比;然而在强场极限下,总解离概率和分支比对单个超快脉冲的谱相位有明显依赖性.通过分析基电子态振动态布居分布,发现啁啾脉冲可以有效调控强场极限下诱导的共振拉曼散射(resonance Raman scattering,RRS)现象,从而导致解离概率和分支比对初始振动态的选择性.研究结果进一步表明,通过选择合适的初始振动态并调控啁啾率的值和符号,可以实现Cl+CH2Br键的优先断裂.该研究为理解超快光场相干控制多原子分子光解反应提供了新的视角.Coherent control of molecular dissociation in ultrafast strong fields has received considerable attention in various scientific disciplines,such as atomic and molecular physics,physical chemistry,and quantum control.Many fundamental issues still exist regarding the understanding of phenomena,exploration of mechanisms,and development of control strategies.Recent progress has shown that manipulating the spectral phase distribution of a single ultrafast strong ultraviolet laser pulse while maintaining the same spectral amplitude distribution can effectively control the total dissociation probability and branching ratio of molecules initially in the ground state.In this work,the spectral phase control of the photodissociation reaction of chlorobromomethane(CH_(2)BrCl)is studied in depth by using a time-dependent quantum wave packet method,focusing on the influence of the initial vibrational state on the dissociation reaction.The results show that modifying the spectral phase of a single ultrafast pulse does not influence the total dissociation probability or branching ratio in the weak field limit.However,these factors exhibit significant dependence on the spectral phase of the single ultrafast pulse in the strong field limit.By analyzing the population distribution of vibrational states in the ground electronic state,we observe that chirped pulses can effectively control the resonance Raman scattering(RRS)phenomenon induced in strong fields,thereby selectively affecting the dissociation probability and branching ratio based on initial vibrational states.Furthermore,we demonstrate that by selecting an appropriate initial vibration state and controlling both the value and sign of the chirp rate,it is possible to achieve preferential cleavage of Cl+CH_(2)Br bonds.This study provides new insights into understanding of ultrafast coherent control of photodissociation reactions in polyatomic molecules.

关 键 词：光解离 相干控制 初始振动态 共振拉曼散射 

分 类 号：O561[理学—原子与分子物理]