SIZE-EFFECTS ON ENERGY RELAXATION AND EXCITED-SPECIES DESORPTION IN KRYPTON CLUSTERS - FLUORESCENCE LIFETIME MEASUREMENTS WITH 10 EV LASER EXCITATION

摘要

Fluorescence lifetime measurements of Kr-N clusters ((N) over bar=2-2000) have been carried out using intense 10 eV laser excitation near P-3(2), metastable atomic energy level. Two principal groups of electronically excited dimers Kr-2* have been found in desorption: dimers, loosely bound near the (P-3(2)+S-1(0)) dissociation limit, ejected from cooled clusters and dimers undergoing vibrational relaxation from hot clusters. The desorption is principally terminated when (N) over bar greater than or equal to 50 at./cluster. The relaxation kinetics seems to converge to the properties of a solid state for 10(2) less than or equal to (N) over bar less than or equal to 10(3) at./cluster. A variation of the Kr-2*(1(u)/0(u)(-)) radiative lifetime, from 264 ns (in gas phase) to 440 ns ((N) over bar=10(2)), has been found, An equilibrium cluster temperature of 57 K has been calculated from this I(N) dependence. (C) 1997 American Institute of Physics. [References: 44]