Enhanced luminescence of oxygen atoms in solid molecular nitrogen nanoclusters.

The article focuses on the enhanced luminescence of the β-group emission (1S → 1D transition) of oxygen atoms in solid molecular nitrogen (N₂) nanoclusters formed by injecting a nitrogen-helium gas mixture discharge into dense cold helium gas. Experiments showed that at low temperatures (~1.5 K), the luminescence is dominated by the α-group emission (2D → 4S transition) of nitrogen atoms stabilized on nanocluster surfaces, while at elevated temperatures (~20–35 K), the β-group oxygen emission intensifies significantly as nitrogen atoms recombine on nanocluster surfaces, forming excited nitrogen molecules that transfer energy efficiently to oxygen atoms stabilized inside the nanoclusters. The presence of trace oxygen impurities (1–10 ppm) in high-purity helium leads to oxygen atoms embedded within the nitrogen nanoclusters, and the relatively short lifetime of the oxygen transition enables an efficient emission channel. Additional experiments varying nitrogen concentration and adding neon support the proposed mechanism of energy transfer and excitation within the nanoclusters.