Programme

P.94 -- Posters, VCTP-50

Date: Thursday, 7 August 2025

Time: 08:30 - 10:00

EFFECT OF DYNAMIC CORE-ELECTRON POLARIZATION ON HIGH-ORDER HARMONIC GENERATION FROM ORIENTED CO MOLECULES

My-Hoa Dam (1), Kim-Ngan H. Nguyen (2), Doan-An Trieu (1,2), Cam-Tu Le (3), Ngoc-Loan Phan (1)

(1) Department of Physics, Ho Chi Minh City University of Education, Ho Chi Minh City, Vietnam (2) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Vietnam (3) Institute for Advanced Study in Technology, Ton Duc Thang University

Previous research on the effect of dynamic core-electron polarization (DCEP) [1] on high-order harmonic generation (HHG) from CO molecules mostly focused on the parallel orientation (0$\circ$), where the molecular axis aligns with the laser polarization [2]. While other works extended the analysis to other orientations, they were limited to only a few representative harmonic orders [3]. A recent study on the 70$^\circ$ orientation revealed notable differences in DCEP effects compared to the parallel case [4], suggesting the orientation-dependent behavior of DCEP effect. Motivated by these findings, this study provides a more comprehensive understanding by investigating the effect of DCEP on the full HHG spectrum across a broad range of orientation angles. To calculate the HHG spectra from CO molecules, we numerically solve the time-dependent Schrödinger equation (TDSE) within the Single-Active Electron (SAE) approximation, incorporating the DCEP potential. The results show that the molecular orientation with respect to the laser polarization strongly impacts the manifestation of DCEP in HHG spectrum, as reflected in the intensity ratio of even harmonics to the two adjacent odd ones, which characterizes the intrinsic asymmetry of the molecule [2]. The time-frequency analysis for HHG emission also provides evidence for the effects of DCEP in the time domain, particularly through the modification in intensity and phase of HHG signals emitted every half cycle of the laser. [1] B. Zhang, J. Yuan, and Z. Zhao, \textit{Phys. Rev. A} \textbf{90}, 035402 (2014). [2] H. T. Nguyen, K. N. H. Nguyen, N. L. Phan, C. T. Le, D. Vu, L. P. Tran, and V. H. Le, \textit{Phys. Rev. A} \textbf{105}, 023106 (2022). [3] N. L. Phan, C. T. Le, V. H. Hoang, and V. H. Le, \textit{Phys. Chem. Chem. Phys.} \textbf{21}, 24046 (2019). [4] H. K. N. Nguyen, M. H. Dam, D. A. Trieu, C. C. Do, and T. N. L. Phan, \textit{HCMUE J. Sci.} \textbf{21}, 1518 (2024).

Presenter: Dam My Hoa