LUMINESCENCE OF NITROGEN AND NEON ATOMS ISOLATED IN SOLID HELIUM

Investigations of metastable N(D-2) and Ne(P-3(2)) atoms isolated in s olid helium have been carried out for the first time. The luminescence spectra and kinetics in the impurity helium solid phase (IHSP), with impurity centers N-2, Ne, Ar, and Kr, show the sensitizing influence o f a neighboring heavy particle on the forbidden N(D-2-S-4) transition. The extremely long-lived (tau approximate to 10(4)s) hyperbolically d ecaying afterglow and thermoluminescence of this transition have been observed in the IHSP. Thermoluminescence studies allowed the determina tion of the energy barrier for pair fusion of neighboring centers. In agreement with calculations the energy barrier of this process which d etermines the IHSP stability turns out to be E(1) = 40 +/- 4 K. The ac tivation energy of the long-lived afterglow stage was found to be E(2) approximate to 7 K, close to the energy of vacancy formation in solid helium. By using laser-induced fluorescence, Ne(P-3(2)) atoms have be en detected in superfluid helium and in the IHSP for the first time. W ithin an experimental accuracy of 0.18 Angstrom their spectral lines w ere unshifted and unbroadened with respect to the gas-phase values.