Influence of solid helium on the luminescence of nitrogen-neon nanoclusters.

We studied the luminescence of neon nanoclusters doped with nitrogen atoms. Neon nanoclusters were collected inside bulk superfluid helium at temperatures below 1.5 K. We found that the spectra of the nitrogen atom α-group had a specific shape with an enhanced narrow line at = 519.9 nm. The measured spectroscopic characteristics of this line, such as the position, narrow linewidth, relatively large intensity, and long lifetime, allow assignment of this line to nitrogen atoms on the surfaces of neon nanoclusters, surrounded by layers of solid helium. This is the first observation of the influence of solid helium on the spectral characteristics of atoms inside the bulk superfluid helium.