Relaxation of Multiple Excitons in ZnCdS and ZnCdS/ZnS Alloy Quantum Dots

IF 1.4 4区化学 Q4 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

Russian Journal of Physical Chemistry B Pub Date : 2025-01-15 DOI:10.1134/S1990793124701380

A. A. Vasin, A. L. Dobryakov, S. Yu. Kochev, O. Yu. Antonova, F. E. Gostev, I. V. Shelayev, A. N. Kostrov, A. V. Aibush, V. A. Nadtochenko

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Abstract

The relaxation dynamics of “hot” and band-edge excitons in ZnCdS (2.8 eV edge exciton) and ZnCdS/ZnS (2.7 eV) quantum dot alloys was studied using femtosecond pump (360 nm, 3.44 eV, 25 fs)— probe (380–700 nm) laser spectroscopy. Transients were studied as a function of the pump pulse energy, which changes the number of excitons. The relaxation of the “hot” exciton is controlled by the Auger mechanism. The decay time of a “hot” exciton depends very weakly on the pump energy and is in the range of 140–190 fs. The decay of a band-edge exciton depends significantly on the pump energy, which suggests an Auger recombination mechanism. The multiexponential transient decay is well described within the stochastic model with only two constants \(k_{i}^{{Auger}}\) and \(k_{i}^{1} = {i \mathord{\left/ {\vphantom {i {{{\tau }_{1}}}}} \right. \kern-0em} {{{\tau }_{1}}}}\).

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ZnCdS和ZnCdS/ZnS合金量子点中多激子的弛豫

利用飞秒泵浦(360 nm, 3.44 eV, 25 fs) -探针（380 ～ 700 nm）激光光谱研究了ZnCdS （2.8 eV）和ZnCdS/ZnS （2.7 eV）量子点合金中“热”激子和带边激子的弛豫动力学。研究了瞬态随泵浦脉冲能量改变激子数目的函数关系。“热”激子的松弛是由俄歇机制控制的。“热”激子的衰变时间对泵浦能量的依赖非常弱，在140 - 190fs范围内。带边激子的衰变很大程度上取决于泵浦的能量，这表明存在俄歇复合机制。用两个常数\(k_{i}^{{Auger}}\)和\(k_{i}^{1} = {i \mathord{\left/ {\vphantom {i {{{\tau }_{1}}}}} \right. \kern-0em} {{{\tau }_{1}}}}\)很好地描述了随机模型中的多指数瞬态衰减。

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来源期刊

Russian Journal of Physical Chemistry B 化学-物理：原子、分子和化学物理

CiteScore

2.20

自引率

71.40%

发文量

106

审稿时长

4-8 weeks

期刊介绍： Russian Journal of Physical Chemistry B: Focus on Physics is a journal that publishes studies in the following areas: elementary physical and chemical processes; structure of chemical compounds, reactivity, effect of external field and environment on chemical transformations; molecular dynamics and molecular organization; dynamics and kinetics of photoand radiation-induced processes; mechanism of chemical reactions in gas and condensed phases and at interfaces; chain and thermal processes of ignition, combustion and detonation in gases, two-phase and condensed systems; shock waves; new physical methods of examining chemical reactions; and biological processes in chemical physics.