外加静电场下CO高次谐波谱  

High order harmonic spectra of CO under external electrostatic field

作　　者：蓝湾 迟晨阳 郭迎春[1] 杨玉军[2] 王兵兵[3,4] Lan Wan;Chi Chen-Yang;Guo Ying-Chun;Yang Yu-Jun;Wang Bing-Bing(School of Physics and Electronic Science,East China Normal University,Shanghai 200241,China;Institute of Atomic and Molecular Physics,Jilin University,Changchun 130012,China;Key Laboratory of Optical Physics,Beijing National Laboratory of Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]华东师范大学物理与电子科学学院,上海200241 [2]吉林大学,原子分子物理研究所,长春130012 [3]中国科学院物理研究所,北京凝聚态物理国家研究中心,光物理重点实验室,北京100190 [4]中国科学院大学,北京100049

出　　处：《物理学报》2023年第13期87-94,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12074418,11774411,92250303)资助的课题。

摘　　要：利用分子在强激光中产生的高次谐波谱可以实现对分子结构及分子中电子迁移动力学过程的探测和研究.本文采用Lewenstein模型,计算了确定取向的CO分子在线偏振光与静电场组合作用下产生的高次谐波谱.结果表明,针对外加静电场相对分子朝向的两种不同指向,高次谐波谱分别展现了双平台结构和拉长的单平台结构.理论分析表明这些谐波谱的结构特点主要来自于不同跃迁通道贡献的相干叠加.本文为极性分子在非对称场下的高次谐波的形成提供了一个清晰的物理图像,对调控极性分子的高次谐波,进而产生可控阿秒脉冲具有科学意义.In this work,we use Lewenstein’s theory to calculate the high order harmonic spectra of CO molecule in a linearly polarized laser field combined with an external electrostatic field.The results show that the characteristics of the high order harmonic spectra of CO molecule depend strongly on the direction of the external static electric field relative to the orientation of CO.Especially,when the direction of the external static electric field points from O to C,the plateau of the harmonic spectrum becomes wider and the cutoff frequency reaches a larger value than the scenario without external static electric field.When the direction of the external static electric field points from C to O,the harmonic spectrum shows a double-plateau structure.Using Lewenstein theory,these phenomena can be understood from the viewpoint that the harmonic generation comes from a coherent superposition of the contributions of two kinds of channels characterized by C-end ionization and O-end ionization.The C(O)-end ionization channel means that the electron is ionized from C(O)end,then accelerated by the driving electric field,finally recombines with its parent molecular ion at either C or O end,emitting the harmonics.For the same harmonic order,the contribution of the C-end ionization channel is greater than that of the the O-end ionization channel.The two kinds of channels emit harmonics in adjacent half period of laser,where the external static electric field causes the cutoff frequency of the harmonic spectrum to increase and decrease in the adjacent half period of the laser field.Especially,when the direction of external static electric field is from the C to O,the cutoff frequency of the harmonic spectrum of the C-end ionization channel decreases,resulting in a higher first plateau in the spectrum.While,the increase of cut-off frequency of the O-end ionization channel will result in a lower second plateau.When the direction of external static electric field is reversed,the cutoff frequency of the harmonics of the C-end channel

关 键 词：CO高次谐波 外加静电场 分子取向 双平台结构 

分 类 号：O441.1[理学—电磁学]