Research into the relaxation mechanism of the exciton in rare gas solids by the study of desorption induced by electronic transitions (DIET)

通过对电子和光子辐照引起的稀有气体固体表面脱附的实验研究，研究了稀有气体固体中激子的动力学特性。我们建立了新的实验系统：(1)用脉冲管制冷机研究固体Kr和Xe的电子激发脱附实验系统，(2)在极高真空条件下研究电子激发引起的脱附实验系统，(3)激光等离子体真空紫外源系统。本研究取得的成果概括如下：(1)测量了固体Ne、Ar、Kr表面光诱导脱附的绝对产额。在厚膜中体激子激发，Ne、Ar和Kr的脱附产额分别为1、0.2和0.01-0.1个原子/光子，(2)考察了电子和光子激发在脱附过程中的差异。(3)我们发现Ne准分子通过空腔喷射机制脱附，其动能约为0.2 eV。脱附的准分子处于最高的振动能级，因为脱附的速度比振动弛豫快得多。(4)提出了固体Ne中和表面激子弛豫级联的模型图，并实验测定了其中的一些分支比。

We have investigated the dynamic aspect of excitons in rare gas solids by the experimental study of the desorption at the surface of rare gas solids induced by electron and photon irradiation.1. We have developed the new experimental systems :(1) system for the electron stimulated desorption study of solid Kr and Xe using a pulse tube refrigerator as a cryostat,(2) system for the desorption induced by electronic excitations study under extremely high vacuum condition,(3) laser plasma vacuum ultra violet source.2. The results achieved in this research project are summarized below.(1) Absolute yields of photo-induced desorption at the surface of solid Ne, Ar, and Kr have been measured. By bulk exciton excitation in a thick film, the desorption yield is 1, 0.2, and 0.01-0.1 atoms/photon for Ne, Ar, and Kr, respectively.(2) We have examined the difference between electron and photon excitations in the desorption processes.(3) We found that Ne excimers were desorbed via the cavity ejection mechanism and had the kinetic enegy of about 0.2 eV.The excimers desorbed were in the highest vibrational level since desorption takes place much faster than vibrational relaxation.(4) The model diagram of the relaxation cascade of excitons in bulk and at surface of solid Ne are proposed and some of the branching ratio in it have experimentally been determined.