FLUORESCENCE STUDY OF DEFECT FORMATION via EXCITON TRAPPING INTO MOLECULAR STATES IN RARE GAS SOLIDS

Abstract

1. I. Ya. Fugol', A.N.Ogurtsov, O.N. Grigorashchenko, and E.V. Savchenko Sov. J. Low Temp. Phys. 18(1), 27 (1992). 2. I. Ya. Fugol', B.V. Savchenko, A. N. Ogurtsov and O.N. Grigorashchenko, Physica B. 190, 347 (1993)Author Institution: Department of Spectroscopy, B. Verkin Institute for LOW Temperature Physics and Engineering, Ukrainian Academy of SciencesInformation on defects is very important for elucidation of mass diffusion and chemical reactions in solids. Recently we reported on the pioneering observation of defect formation induced by exciton self-trapping into molecular states in Rare Gas Solids. The paper reports physics of this phenomenon is based on the trapping of electronic excitation energy by the lattice and its conversion to the kinetic energy of atomic motion. The paper reports new data on molecular hosts in Kr matrix. The electronic subsystem was excited by an electron beam of subthreshold energy at low temperatures. So, the conditions of the experiments excluded the classical knock-on and thermally-activated mechanisms of defect formation. The defects were detected by means of vacuum ultraviolet fluorescence spectroscopy. The experimental study of time evolution of fluorescence spectra revealed a build-up of stable point defects in the sampled. It is shown that the defect formulation is induced by exciton trapping into molecular states of both the matrix and the impurity centers. The efficiency of defect formation as a factor of the parameters of electronic states of molecular centers was analyzed. The excited state mechanism which involves the off-center displacement of molecular center was verified. Based on the experimental data the electronically induced mechanism of mass diffusion was suggested