Programme

O.7 -- Oral, VCTP-49

Date: Wednesday, 31 July 2024

Time: 11:35 - 12:00

Multielectron effects in High harmonic generation of HCN: Depending on laser pulse parameters

Duong D. Hoang-Trong (1), Ngoc-Loan Phan (1), Doan-An Trieu (1), and Van-Hoang Le (1)

(1) Ho Chi Minh City University of Education, 280 An Duong Vuong Street, Ward 4, District 5, Ho Chi Minh City 72711, Vietnam

In recent decades, the progress of laser technologies has resulted in the discovery of various nonlinear effects [1-4]. These nonlinear effects, such as above-threshold ionization (ATI), high-energy ATI (HATI), nonsequential double ionization (NSDI), and high-order harmonic generation (HHG) [1-4], have potential to imply extracting time-resolved imaging and investigating dynamics within atoms and molecules [5, 6]. As a result, a deep physics understanding and accurate theoretical explanations of these nonlinear effects that are consistent with experimental observations are required. Solving time-dependent Schrödinger equation (TDSE) using the single active electron (SAE) model which is a low-cost method is a common way for investigating these phenomena theoretically [7-9]. Previous works ansatz highest occupied molecule orbital (HOMO) dominantly contributes to highly nonlinear spectra, such as HHG, compared to lower-lying orbitals [10-12]. However, subsequent studies have revealed the imprint of lower-lying orbitals. The coupling between HOMO and lower-lying orbitals leads to electron-electron interactions between MOs, called the multielectron effect. This effect offers to extract electron-electron dynamics on attosecond time scales, a significant topic in Strong-field Physics. To determine the contribution of each MO, an advanced approach such as time-dependent density-functional theory (TDDFT) is applied [13-15]. However, due to the new target, HCN molecules, there is disagreement in these researches about the contribution of HOMO and HOMO-1 [13, 15]. Furthermore, these simulations did not consider the permanent dipoles of each MO, which is required for dissymmetrical molecules like HCN. In this work, we discerned the contribution of HOMO and HOMO-1 in HHG spectra of HCN by solving the TDSE with SAE approximation that mimics the energies and permanent dipoles of both HOMO and HOMO-1. We explored the imprint of multielectron and the competition in contributing to HHG spectra of HOMO and HOMO-1 depending on the laser parameters. This explained the disagreement in previous studies [13, 15]. [1] L’Huillier, K. J. Schafer and K. C. Kulander, J. Phys. B: At. Mol. Opt. Phys., 1991, 24, 3315. [2] J. L. Krause, K. J. Schafer and K. C. Kulander, Phys. Rev. Lett., 1992, 68, 3535. [3] P. B. Corkum, Phys. Rev. Lett., 1993, 71, 1994. [4] M. Lewenstein, P. Balcou, M. Y. Ivanov, A. L’Huillier and P. B. Corkum, Phys. Rev. A, 1994, 49, 2117. [5] M. Lewenstein, K. C. Kulander, K. J. Schafer and P. H. Bucks-baum, Phys. Rev. A, 1995, 51, 1495. [6] J. Itatani, J. Levesque, D. Zeidler, H. Niikura, H. Pépin, J.-C. Kieffer, P. B. Corkum and D. M. Villeneuve, Nature, 2004, 432, 867. V.-H. Le, A.-T. Le, R.-H. Xie and C. D. Lin, Phys. Rev. A, 2007, 76, 013414. [7] M. Abu-Samha, L. B. Madsen, N. I Shvetsov-Shilovski, arXiv (preprint) https://arxiv.org/abs/2404.14254. [8] H. T. Nguyen, K.-N. H. Nguyen, N.-L. Phan, C.-T. Le, D. D. Vu, L.-P. Tran, and V.-H. Le, Phys. Rev. A, 2022, 105, 023106. [9] K.-N. H. Nguyen, N.-L. Phan, C.-T. Le, D. D. Vu, and V.-H. Le, , Phys. Rev. A, 2022, 106, 063108. [10] M. Peters, T. T. Nguyen-Dang, E. Charron, A. Keller and O. Atabek, Phys. Rev. A, 2012, [11] 85, 053417. [12] J. Xu, H.-L. Zhou, Z. Chen and C. D. Lin, Phys. Rev. A, 2009, 79, 052508 [13] X. Chu, Phys. Rev. A, 2023, 108, 013116. [14] X. Chu, Phys. Rev. A, 2024, 109, 053103. [15] Koushki, J. Mol. Model., 2023, 29, 137.

Presenter: Hoàng Trọng Đại Dương