奇偶高次谐波光谱学研究进展  

Advances on odd-even high-harmonic spectroscopy

作　　者：车佳殷 陈彦军[1] Jiayin Che;Yanjun Chen(College of Physics and Information Technology,Shaanxi Normal University,Xi’an 710119,China)

机构地区：[1]陕西师范大学物理学与信息技术学院,西安710119

出　　处：《科学通报》2021年第8期871-877,共7页Chinese Science Bulletin

基　　金：国家重点研发计划(2018YFB0504400);国家自然科学基金(91750111);中央高校基本科研业务费创新团队项目(GK201801009)资助。

摘　　要：不对称分子由于对称破缺在强激光场中会辐射奇次和偶次谐波.研究表明,奇偶谐波辐射在频域上具有显著不同的特性.通过建立奇偶谐波辐射理论模型,进一步的研究指出,奇偶谐波携带着系统的不同信息,可通过提取奇偶谐波各自的特征信息,整合反演出系统的全部信息.上述奇偶分辨的高次谐波光谱学研究思路和相关理论模型已被广泛地应用于不对称分子的超快探测过程中,例如,可以用于重构不对称分子轨道,探测极性分子核的动力学,标定不对称分子取向度,探测多中心分子结构等;还可以用于探测不对称分子的形状共振和电荷输运等.奇偶高次谐波光谱学的研究与发展对推动谐波辐射在阿秒科学和化学反应中的应用发挥着积极作用.High harmonic generation(HHG)has important applications in attosecond science,such as generating attosecond pulses and probing the structure and the electron dynamics of atoms and molecules with attosecond resolution.Different from symmetric cases,because of symmetry breaking,asymmetric molecules can emit both odd-order and even-order harmonics in strong single-color laser fields.Ultrafast probing of polar molecules with HHG is a hot issue in recent years,as polar molecules are generally very active in chemical reactions.With dividing the HHG signal into odd and even parts,recent studies have shown that odd and even harmonics from asymmetric molecules have different properties in frequency domain.To explain this typical difference,a theoretical model has been developed to describe the generation mechanism of odd versus even HHG from asymmetric molecules.It is shown that during the process of tunneling,the gerade component of the asymmetric orbital plays a dominating role and the contributions of the ungerade component can be neglected.Thereafter,the recombination of the rescattering electron with the gerade(ungerade)component of the asymmetric orbital mainly contributes to the emission of odd(even)harmonics.As a result,odd and even harmonics carry different information of the asymmetric system.Recently,it has been shown that the contributions of the ungerade component of asymmetric orbital to ionization are strongly suppressed due to the destructive intramolecular interference.This suppressing effect is general for strong-field ionization of polar molecules,implying that the theoretical model of odd-even HHG holds for a wide parameter region.These results open a new perspective for probing polar molecules with odd-even HHG.Specifically,when it is relatively difficult to read the information of the molecular structure or the electron dynamics through the whole harmonic spectrum of asymmetric molecules,one can extract the characteristic information of odd or even harmonic separately,then this characteristic informa

关 键 词：奇偶谐波辐射 不对称分子 超快探测 阿秒 

分 类 号：O433[机械工程—光学工程]