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We studied luminescence accompanied by an injection of nitrogen–krypton–helium gas mixtures after passing radiofrequency discharge into dense cold helium gas. In the cold helium gas N2–Kr nanoclusters were formed, with a core of Kr atoms and N2 molecules on the surface. Atomic nitrogen and oxygen resided in the N2 surface layers. When the temperature in the observation zone was in the range of 20–36 K, we observed enhanced emission of oxygen atom β-group and molecular nitrogen Vegard–Kaplan bands from N2–Kr nanoclusters. At these temperatures, nitrogen atoms efficiently recombine on the surface of nanoclusters with the formation of exited nitrogen molecules, leading to enhanced emission of Vegard–Kaplan bands. Simultaneously, the energy transfer from exited nitrogen molecules to the oxygen atoms enhanced O atom β-group emission. 

We studied luminescence accompanied an injection of the nitrogen-helium gas mixture after passing discharge into dense cold helium gas. Initially, when the experimental beaker was filled with superfluid helium and the nitrogen-helium gas was injected into bulk superfluid helium at T ≈ 1.5 K, the dominant band in the emission spectra was the α-group of nitrogen atoms. At these conditions, the nanoclusters of molecular nitrogen with high concentrations of stabilized nitrogen atoms were formed. When superfluid helium was evaporated from the beaker and the temperature at the bottom of the beaker was increased to T ≈ 20 K, we observed a drastic change in the luminescence spectra. The β-group of oxygen atoms was dominated in the luminescence spectra, and the emission of the α-group became small. At high temperatures (T ≈ 20 K), most of the nitrogen atoms recombine on the surface of N2 nanoclusters with the formation of excited nitrogen molecules. We explained the effect of the enhancement of β-group emission by effective energy transfer from excited nitrogen molecules to the stabilized impurity oxygen atom inside N2 nanoclusters.