近日，美国蒙大拿大学Xi Chu团队研究了在显著偶极矩影响下的分子高谐波产生。这一研究成果发表在2026年2月3日出版的《物理评论A》杂志上。

基于含时密度泛函理论，研究组分析了大的永久偶极矩如何影响高次谐波产生。以LiH分子为例，通过系统比较激光偏振方向平行与垂直于分子轴时获得的光谱，研究组识别出由偶极矩引起的显著斯塔克位移所产生的独特特征。在平行取向下，这些位移拓宽了共振条件，并显著增强了阈值以下的谐波，形成了平台状结构。

在瞬态电离势最大值附近还出现了明显的双中心干涉极小点。此外，每个光学半周期内斯塔克位移的变化及其在相邻半周期间的交替符号，导致了隧穿、传播和复合过程的不对称性。这些不对称性驱动了干涉效应，表现为高次谐波谱的平台区和截止区附近出现谱线分裂与蓝移现象。

附：英文原文

Title: Molecular high-harmonic generation under the influence of a significant dipole moment

Author: Xi Chu

Issue&Volume: 2026/02/03

Abstract: Using time-dependent density-functional theory, we investigate how a large permanent dipole moment modifies high-harmonic generation (HHG). Using LiH as an example, by systematically comparing spectra obtained with laser polarization parallel and perpendicular to the molecular axis, we identify distinctive features arising from pronounced Stark shifts induced by the dipole. In the parallel orientation, these shifts broaden resonance conditions and strongly enhance below-threshold harmonics, producing a plateaulike structure. A pronounced two-center interference minimum also appears near the maximum transient ionization potential. Furthermore, the variation of Stark shifts within each half optical cycle (HOC), together with their alternating signs between consecutive HOCs, introduces asymmetries in tunneling, propagation, and recombination. These asymmetries drive interference that manifests as spectral splits and blueshifts in the plateau and near-cutoff regions of the HHG spectrum.

DOI: 10.1103/rphy-8kg7

Source: https://journals.aps.org/pra/abstract/10.1103/rphy-8kg7