Seminar khoa học của TS. Lê Thị Cẩm Tú, TS. Lê Nguyễn Minh Thông và ThS. Nguyễn Huỳnh Kim Ngân

Vào 14h00, ngày 04/10/2024 Viện IAST tổ chức buổi trao đổi học thuật tại Phòng họp B với nội dung chi tiết như sau: 

ThS. Nguyễn Huỳnh Kim Ngân trình bày về "Effect of Dynamic Core-Electron Polarization on Frequency Shift in High-Order Harmonic Generation from CO Molecules"

Tóm tắt: 

 The multi-electron effect is recognized as a significant factor in simulating the behavior of laser-matter interactions. A prominent manifestation of this effect is dynamic core-electron polarization (DCeP). In this study, we investigate the role of DCeP in high-order harmonic generation (HHG) emitted by CO molecules under the influence of a few-cycle laser.

By theoretically examining the formation of harmonic orders through the analysis of sub-cycle interference between adjacent attosecond bursts, we identify a distortion in harmonic orders caused by phase asymmetry of the attosecond bursts. This finding suggests that the DCeP-induced phase difference in the time domain can directly influence the harmonic orders, leading to frequency shifts in the HHG spectra.

TS. Lê Thị Cẩm Tú trình bày về "Exploring the Relation of Harmonic-Order Formation and Dynamical Phase Difference via the Bohmian Trajectory Perspective "

Tóm tắt:

We have recently explored the manifestation of dynamic core-electron polarization in the high-order harmonic generation of asymmetric CO molecules offered by the Bohmian perspective. Therein, a few-cycle pulse with only one burst from one side of the molecule, the C end in that case, responsible for the high-energy region of the harmonic spectrum is utilized, so all essential dynamics is encoded in a single central trajectory whose initial position is near the C atom, denoted as BT(P). If the number of optical cycles increases, the process can occur at two non-equivalent CO molecules' ends. By following up on the evolution of individual Bohmian trajectories and their dynamics, we can identify the central trajectories and elucidate the dynamics of the harmonic process. Particularly, when the molecule is antiparallel to the laser electric polarization, the accelerations, and the harmonic spectra show that despite smaller weights contributing to the harmonic spectrum, the trajectories with initial positions located near the O atom denoted as BT(Ns) are non-negligible in reproducing the harmonic-spectrum structure, particularly in the cutoff-energy region.

 TS. Lê Nguyễn Minh Thông trình bày về "First-principles study on gas sensing properties of MXenes materials"

Tóm tắt:

 Novel two-dimensional MXene materials attract much attention from technology applications relying on their diverse structural compositions and outstanding physical-chemical features. With intriguing properties, those graphene-like structures have been extensively studied for gas adsorption and detection. In this report, the structural-property correlations and gas-sensing performances for many MXene stoichiometries have been discussed in light of computational approaches. Surface terminations are important to determine the adsorbate-adsorbent interactions. Accordingly, sensing mechanisms are introduced in detail for suitable capturing of a variety of adsorbates, i.e., for both polar and nonpolar organic molecules. Pre-calculated parameters derived from density functional theory are usable for a theoretical approach based on the non-equilibrium Green function to evaluate sensing properties.