Programme

I.7 -- Invited, VCTP-46

Date: Tuesday, 5 October 2021

Time: 14:00 - 14:30

Influence of dynamic core-electron polarization of co molecules on odd-even high-order harmonic generation

Ngoc-Loan Phan(1), Hien T. Nguyen (2), Kim-Ngan H. Nguyen (1), Cam-Tu Le (3), Van-Hoang Le (1)

(1) Ho Chi Minh City University of Education (2) Tay Nguyen University (3) Ton Duc Thang University

Recently, the investigation of high-order harmonic generation (HHG) emitted from polar molecules such as CO, NO, OCS has been paid much attention. In the difference from HHGs of atoms or symmetric molecules that contain only odd harmonics, the HHGs emitted from polar molecules possess both odd and even harmonics due to the symmetry breaking of the molecule itself [1,2]. Therefore, the quantity characterized by the ratio of the intensities between the neighboring even and odd harmonics, called the even-to-odd ratio, is substantial in probing molecular dynamics or molecular ensemble [3]. In general, most of the theories are based on the single-active electron approximation, in which only the outermost electron can be ionized and then recombined into the parent ion to emit HHG. Meanwhile, the core electrons are considered “frozen” associated with the nuclei. However, recent studies have proved the significant influence of the multielectron effect on the ionization rate, and as a consequence, the HHG intensity [4,5]. But the impact of the core-electron on the even-to-odd ratio is still desirable. This report presents the influence of dynamic core-electron polarization (DCeP) of CO molecules on the even-to-odd ratio. The HHG is theoretically simulated by numerically solving the time-dependent Schrӧdinger equation. We indicate that the DCeP considerably affects the even-to-odd ratio. Notably, considering the DCeP effect makes the even-to-odd ratio is compared to the experimental data. We then clarify that this influence is attributed to the effect of DCeP not only on the intensity but also the phase difference of the adjacent attosecond harmonic bursts. [1]. Frumker, E. et al. Probing Polar Molecules with High Harmonic Spectroscopy. Phys. Rev. Lett. 109, 233904 (2012). [2]. Phan, N.- L., Le, C. T., Hoang, V. H. & Le, V. H. Odd-even harmonic generation from oriented CO molecules in linearly polarized laser fields and the influence of the dynamic core-electron polarization. Phys. Chem. Chem. Phys. 21, 24177–24186 (2019). [3]. Phan, N.-L. et al. General characterization of partially oriented polar molecules by the time-frequency profile of high-order harmonic generation. Phys. Rev. A 102, 063104 (2020). [4]. Le, C.-T., Hoang, V.-H., Tran, L.-P. & Le, V.-H. Effect of the dynamic core-electron polarization of CO molecules on high-order harmonic generation. Phys. Rev. A 97, 043405 (2018). [5]. Zhang, B., Yuan, J. & Zhao, Z. Dynamic orbitals in high-order harmonic generation from CO molecules. Phys. Rev. A 90, 035402 (2014).

Presenter: Phan Thi Ngoc-Loan