Seminar by Dr. Hoang Manh Ha, Dr. Man Minh Tan and Dr. Dinh Thanh Binh

TDTU, 03/06/2025

At 2:00 p.m., June 6, 2025, the IAST Institute organized an seminar at Room 604 - Office in Hanoi with detailed content as follows:

1/ PhD. Hoang Manh Ha presented "Spectroscopic and Judd-Ofelt analysis of the Pr3+ ions doped LaF3 nanocrystals"

Abstract:

Pr3+ ions doped hexagonal LaF3 nanocrystals were synthesized by hydrothermal method. The crystal structure of the obtained samples was identified by XRD, and the results showed that all the phases were indexed to scheelite structure. The spectroscopic properties of LaF3:Pr3+ nanocrystals have been investigated using optical absorption and emission spectra at room temperature. From the measured intensities of various absorption band, the Judd–Ofelt parameters Ωλ (λ = 2, 4, 6) have been evaluated. For LaF3:5%Pr3+ sample, the bonding parameter δ = 0.499, Ω2 = 0.325 x 10-20 cm2, Ω4 = 0.670 x 10-20 cm2 and Ω6 = 2.519 x 10-20 cm2  with the r.m.s. deviation of oscillator strengths σrms = ±0.431 x 10-6. Using these J–O parameters, various radiative parameters such as radiative transition probabilities AR, radiative lifetime τR, branching ratios βR  and stimulated emission cross-section σem(λp) were calculated from excited states of 3P1 and 3P0 levels.

2/ PhD. Man Minh Tan presented "Synthesis and dual-channel optical properties of Mn-doped ZnSe quantum dots"

Abstract:

We have successfully demonstrated the colloidal hot-injection process to easily obtain the Mn-doped ZnSe quantum dots (QDs) with a size of about 4–5nm, and d-spacing is 0.31nm, corresponding to the (111) lattice plane of ZnSe. Experimental results show that UV–vis absorption and fluorescence spectra were recorded to elucidate the role of Mn2+ ions substituted into ZnSe, which results in the carrier transfer of luminescent sites by a small amount of Mn2+ dopant. The small size of the Mn-doped ZnSe QDs offers intriguing opportunities for their application in photonics, bioimaging, and spintronics devices.

3/ PhD. Dinh Thanh Binh presented "Particle accelerator: Industrial applications and the search for new Z boson"

Abstract:

Particle accelerator long has been used in fundamental research. In this talk I will first briefly review particle accelerators and some of its sociometric applications related to medical treatment, environmental monitoring, food quality, energy and aerospace technologies. Finally I will talk about the search for new neural gauge boson Z' at CLIC base on electron and gamma collisions.