He Shan, Liu Dong, Li Xueyang, Chu Junzhi, Guo Jingwei, Liu Jinbo, Hu Shu, Sang Fengting, Jin Yuqi
Key Laboratory of Chemical Lasers, Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian , 116023 , P. R. China.
University of Chinese Academy of Sciences , Beijing , 100049 , P. R. China.
J Phys Chem A. 2018 Jun 21;122(24):5361-5369. doi: 10.1021/acs.jpca.8b03238. Epub 2018 Jun 11.
The kinetic processes for the Xe (6p[1/2]) atoms in Kr, Ar, Ne, and He buffer gases were studied. We found that Kr, Ar, and Ne atoms can be used to switch the amplified spontaneous emission (ASE) channel from 3408 nm (6p[1/2]-6s'[1/2]) to 3680 nm (5d[1/2]-6p[1/2]), while Xe and He atoms do not show such a phenomenon. This ASE channel switch is mainly ascribed to the fast transfer of 6p[1/2] → 5d[1/2]. On the basis of the rate equations for two-state coupling (energy-transfer processes between the two states are very rapid), the reason why the ASE channel switch effect normally coincides with a double exponential decay of the spontaneous emission at 828 nm (6p[1/2]-6s[3/2]) is explained. The actual situations in Xe, Ar, Ne, and He follow this rule. However, the strictly single exponential decay of the spontaneous emission at 828 nm and strong ASE channel switch effect simultaneously emerge in Kr. This indicates that the transfer of 6p[1/2] → 5d[1/2] in Kr does not occur via two-state coupling, but via two steps of near-resonance collision through the 5s[3/2] (Kr) state as the intermediate state (6p[1/2] → 5s[3/2] (Kr) → 5d[1/2]). In addition, we found Xe (6p[1/2]) atoms strongly tend to reach the 6p[3/2], 6p[3/2], and 6p[5/2] states through the 5s[3/2] (Kr) state as the intermediate state in Kr. The 5s[3/2] (Kr) state plays a very important role in the energy-transfer kinetics for the Xe (6p[1/2]) atoms. Kr is probably an excellent buffer gas for laser systems based on Xe.
研究了Xe(6p[1/2])原子在Kr、Ar、Ne和He缓冲气体中的动力学过程。我们发现，Kr、Ar和Ne原子可用于将放大自发辐射(ASE)通道从3408 nm(6p[1/2]-6s'[1/2])切换到3680 nm(5d[1/2]-6p[1/2])，而Xe和He原子未表现出这种现象。这种ASE通道切换主要归因于6p[1/2]→5d[1/2]的快速转移。基于双态耦合的速率方程(两态之间的能量转移过程非常迅速) ，解释了ASE通道切换效应通常与828 nm(6p[1/2]-6s[3/2])处自发辐射的双指数衰减相一致的原因。Xe、Ar、Ne和He中的实际情况遵循这一规律.然而,Kr中同时出现了828 nm处自发辐射的严格单指数衰减以及强烈的ASE通道切换效应。这表明，Kr中6p[1/2]→5d[1/2]的转移不是通过双态耦合发生的.而是通过以5s3/2态为中间态的两步近共振碰撞发生的(6p[1/2]→5s3/2→5d[1/2])。此外，我们发现，在Kr中，Xe(6p[1/2])原子强烈倾向于通过以5s3/2态为中间态到达6p[3/2]、6p[3/2]和6p[5/2]态。5s3/2态在Xe(6p[1/2])原子的能量转移动力学中起着非常重要的作用。Kr可能是基于Xe的激光系统的优良缓冲气体。
