OBSERVATION OF VISIBLE AND INFRARED LUMINESCENCE OF XENON CLUSTER IONS - ROLE OF RADIATIVE PROCESSES IN THE FORMATION OF CLUSTER IONS AND THEIR SIZE AND TEMPERATURE

Observations of continuous luminescence bands in the visible and infra red spectral ranges of Xe-N(+) cluster ions (N = 10-2200) are reported . Based on measured luminescence excitation yields, they are assigned to radiative transitions related to the P-2(1/2) --> P-2(3/2) transiti on of atomic Xe ions. The transition energy of one band at similar to 1.9 eV shows a very unusual spectral shift which is proportional to th e logarithm of the cluster size, and which can be explained using the Frenkel exciton model. The implications of the size and temperature de pendencies for the relaxation processes in ionized clusters are discus sed.