Analysis of the impacts of reactant molecular beam velocity spreads on product velocity resolution in crossed beam experiments  

交叉分子束实验中反应物分子束速度分布对产物速度成像分辨率的影响分析

作　　者：Yufan Ding Min Cheng Hong Gao 丁育凡;程敏;高蕻(中国科学院化学研究所,北京分子科学国家研究中心,北京100190;中国科学院大学,北京100049)

机构地区：[1]Beijing National Laboratory for Molecular Sciences(BNLMS),Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Journal of Chemical Physics》2024年第6期814-822,I0042,I0043,共11页化学物理学报(英文)

基　　金：supported by the National Natural Science Foundation of China(No.22373107);Beijing National Laboratory for Molecular Sciences(BNLMSCXXM-202406);Hong Gao is also supported by the Innovation Capability Support Program of Shaanxi Province(2023-CX-TD-49).

摘　　要：Owing to its convenience and accuracy in providing detailed information about quantum state populations and angular distributions of reaction products,the velocity map imaging technique has been extensively employed in crossed beam experiments for product detection.In crossed beam experiments,the two reactant beams always exhibit certain spreads in both magnitude and direction of the velocity,which will blur the scattered product images and lower the resolution of product detection.To systematically investigate the influence of reactant velocity spreads on the resolution of product detection in crossed beam experiments,a general model based on velocity vector analysis is constructed and presented here.The impacts of spreads of the magnitude and direction of the reactant velocities on the image resolution under three typical experimental conditions are analyzed,and ways for improving the resolution are briefly discussed.Guided by the above analysis,a fine adjustment of the Ar^(+)ion beam was performed,and the product image resolution for the charge transfer reaction Ar^(+)(^(2)P_(3/2))+N_(2)is effectively improved,particularly in the backward scattering region,which provides more accurate information on the reaction dynamics.由于能方便和准确地测量反应产物的量子态分布和角度分布等详细信息,速度成像技术被广泛地应用于交叉分子束实验的产物检测中.在交叉分子束实验中,两个反应物分子束的速度大小和方向总是具有一定的分布,这将使产物的速度成像图变得模糊,分辨率降低.为了系统地研究反应物速度分布对交叉分子束实验中产物成像分辨率的影响,本文构建了一个基于速度矢量分析的通用模型.利用该模型分析了三种典型实验条件下反应物的速度矢量分布对产物速度成像分辨率的影响,并简要讨论了提高分辨率的方法.在上述分析的指导下,对Ar^(+)离子束进行了精细调控,有效提高了电荷转移反应Ar^(+)(^(2)P_(3/2))+N_(2)的产物速度成像分辨率(尤其是在产物的后向散射区域),从而提供了更准确的反应动力学信息.

关 键 词：Crossed molecular beam Molecular beam Velocity-map imaging Monte Carlo simulation Product velocity resolution 

分 类 号：O57[理学—粒子物理与原子核物理]