Ultrafast Quantum Dynamics and Emerging Technologies toward Sustainable Development

Vào 14h00, ngày 30/09/2026, Viện IAST tổ chức buổi trao đổi học thuật tại Phòng họp Thư viện lầu 5, cơ sở Tân Hưng với nội dung chi tiết như sau:

1/  TS. Nguyễn Huỳnh Kim Ngân

Tên báo cáo: From odd-even harmonics to attosecond dynamics: Probing molecular asymmetry through high-order harmonic generation
Tóm tắt: High-order harmonic generation (HHG) from oriented polar molecules provides a powerful way to probe molecular asymmetry on ultrafast timescales [1]. In particular, the appearance of both odd and even harmonics carries information about the asymmetry between the attosecond bursts generated when the electron recollides with the two opposite sides of the molecule. In this work, we establish a direct connection between the odd-even harmonic spectrum and the underlying attosecond emission dynamics. We show that the spectral intensity ratio and phase difference between neighboring odd and even harmonics can be mapped onto the amplitude and phase asymmetry of consecutive attosecond bursts. More importantly, this mapping is analytically invertible, enabling the microscopic asymmetry to be retrieved directly from spectral observables. Using three-dimensional time-dependent Schrödinger equation simulations of oriented CO molecules, we demonstrate that the retrieved quantities closely reproduce the directly calculated properties of the attosecond bursts and are largely insensitive to laser intensity and wavelength within the tunneling regime. Our results show that odd-even HHG can serve not only as a signature of molecular asymmetry, but also as a quantitative probe of subcycle electron dynamics.

2/  ThS. Triệu Đoan An 

Tên báo cáo: Moderate-terahertz-induced plateau expansion of high-order harmonic generation to soft X-ray region
Tóm tắt: Extending the high-harmonic cutoff with experimentally accessible fields is essential for advancing tabletop coherent extreme-ultraviolet (EUV) and soft X-ray sources. Although terahertz (THz) assistance offers a promising route, cutoff extension at weak, laboratory-accessible THz strengths remains poorly understood. In this report, we investigate THz-assisted high-order harmonic generation (HHG) using time-dependent Schrödinger equation simulations supported by classical analysis. By mapping the plateau evolution versus THz field strength, we demonstrate that even weak THz fields extend the cutoff, producing a pronounced “fish-fin” structure whose dominant branches saturate near Ip + 8Up. We attribute this extension to long electron excursions spanning multiple optical cycles before recombination. Our results establish that this cutoff-extension mechanism is robust across atomic species and driving parameters, indicating that laboratory-scale THz fields enable practical cutoff control and access to high-energy HHG.

3/  TS. Ramanathan Subramanian

Tên báo cáo: Synthesis of biomass-derived carbon from expired iron tablets coupled with PMS for tetracycline degradation: A non-radical pathway, Animal survival study
Tóm tắt: The improper disposal of expired pharmaceutical products and the persistent occurrence of antibiotic pollutants in aquatic systems pose significant environmental challenges. This work demonstrated the volarization of expired iron supplement tablets (a primary pharmaceutical solid waste) into iron doped carbon (Fe-TBC) for efficient degradation of tetracycline (TC) contaminant in water bodies using peroxymonosulfate (PMS) activation. The upcycled Fe-TBC samples were scrutinized using comprehensive physicochemical characterization to explore its surface texture, functional group features and magnetic properties. The physico-chemical characterization results revealed a surface defect rich, oxygen functionalized (i.e., –OH, C=O, C–O–C) carbon architecture with homogeneously distributed Fe^2+/3+ domains with strong magnetic feature, which can induce catalytic active sites for PMS activation. The catalytic degradation analysis was explored with TC degradation in a series of PS, PMS, Fe-TBC/PS, and Fe-TBC/PMS. On comparison, Fe-TBC/PMS exhibited higher degradation efficiency (97.2%) over TC than Fe-TBC/PS (74.3%) system, PMS and PS alone. The surface functionalities on the Fe-TBC facilitated efficient TC degradation, whereas the embedded Fe species predominantly promoted selective singlet oxygen (¹O₂) and pave a way for non-radical degradation pathway. In addition, the scavenge and cycle stability test confirmed the non-radical degradation pathway and excellent durability (89.3%) even after five cycles. Besides, the toxicity assessment on degraded water samples exposed no morphological abnormalities in zebrafish (Danio rerio) bioassays, confirming the effective detoxification of TC. Hence, the proposed Fe-TBC/PMS framework for TC degradation offers a sustainable waste-to-resource strategy for advanced wastewater treatment applications.