10min:

R. E. BOLTNEV, E. B. GORDON, V. V. KHMELENKO, I. N. KRUSHINSKAYA, M. V. MARTYNENKO, A. A. PELMENEV, E. A. POPOV, Institute of Energy Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation; A. F. SHESTAKOV, Institute of Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation.

A solidification of liquid helium around impurity particles injected in its volume results in IHSP (Impurity-Helium Solid Phase) formation , so these particles can be stabilized with inert environment during long time. Particular interest is stabilization of metastable particles. The capture of N(²D) atoms from discharge allows to save ones at T=1.5 K during 10⁴ s - time comparable with their lifetime, 4.4× 10⁴ s. Nevertheless, even small temperature increase (<0.1 K) causes the luminescence on the ²D - ⁴S transition. It was explained as thermoactivated association of neighbouring centers of IHSP, N+N₂ or N+Rg, which partially removes the prohibition because of "heavy particle effect" . The main part of stabilized nitrogen atoms is in the ground state ⁴S, so thermoactivated mobility leads to the pair recombination N+N or N+O (O₂ presents as trace in condensed gas mixture). The results presented in report confirm that heating of IHSP samples causes a blue emission which can be assigned to excited states of N₂ or NO.

Acknowledgement: The work was carried out with support from Russian Foundation for Basic Research (Grant 99-03-33261).