Electronic radiative transition in He(21,3S)-Ne weakly bound molecules. Temperature dependence

The metastable states He(1s2s2(1,3)S) are the champions in terms of radiative lifetime of neutral atomic states, similar to 20.10(-3) s and similar to 7.10(3) s for the single and triplet states respectively. However in numerous applications one deals with a metastable atom surrounded by buffer gas atoms. In the case of low temperatures the processes of recombination lead to the formation of clusters and dimers containing exited He* atoms. The present calculations reveal that lifetimes of quasi-bound molecules He(2(1,3)S)Ne are lowered by a factor equal to similar to 10(-9) - 10(-7) in comparison with free metastable atoms. Temperature dependences of lifetimes are presented as well as averaged spectral line shapes. It is shown that radiative transitions mainly lead to the formation of free He and Ne atoms in their ground-state with the kinetic energy of relative motion in the range of 0-0.03 eV.