No abstract

The stabilization and recombination of nitrogen atoms N(4S) in nitrogen-helium and nitrogen–neon-helium condensates obtained by the injection of impurity particles from a gas discharge into bulk superfluid helium are investigated by the EPR method. It is established that the stabilized nitrogen atoms reside inside and on the surface of impurity clusters forming a porous structure in the bulk superfluid helium. The possibility of increasing the specific energy of impurity–helium condensates by increasing their density through mechanical pressing is investigated. For nitrogen-helium condensates an eightfold increase in the specific energy is achieved. The recombination loss of N(4S) upon heating of impurity–helium condensates in the temperature range 1.7–7 K is detected. This permits verification of the mechanism of thermoluminescence of impurity–helium condensates.

We have studied thermostimulated luminenscence and electron emission of nitrogen films and nanoclusters containing atomic nitrogen free radicals. Thermostimulated electron emission from N 2 nanoclusters was observed for the first time. Thermostimulated luminescence spectra obtained during N 2 -He sample destruction are similar to those detected from N 2 films pre-irradiated by an electron beam. This similarity reveals common mechanisms of energy transfer and relaxation. The correlation of the luminescence intensity and the electron current in both systems points to the important role of ionic species in relaxation cascades. A sublimation of solid helium shells isolating nitrogen nanoclusters is a trigger for the initiation of thermostimulated luminescence and electron emission in these nitrogen-helium condensates. PACS: 78.60.Kn Thermoluminescence; 79.75.+g Exoelectron emission.