Studies of the Structures of Nitrogen-Neon Nanoclusters Immersed into Superfluid Helium-4

We studied the electron spin resonance (ESR) spectra of nitrogen atoms stabilized in nitrogen-neon nanoclusters immersed in superfluid \(^4\) ${}^4$ He. The nanoclusters were formed during the condensation of the products of the discharge in N \(_2\) ${}_2$ –Ne–He gas mixtures into bulk superfluid \(^4\) ${}^4$ He at temperature 1.5 K. We studied nanoclusters formed by injection of gas mixtures with different ratios of heavy impurities in the helium N \(_2\) ${}_2$ /(Ne + N \(_2\) ${}_2$ ) ranging from 2% to 90%. Analysis of the ESR spectra of nitrogen atoms stabilized in nitrogen-neon nanoclusters provides important information about the environment of the stabilized atoms and a shell structure of the nanoclusters was revealed. For all samples studied, preferential stabilization of N atoms on the surfaces of the nanoclusters was observed. Annealing of the collection of the nanoclusters in the temperature range 1.1–10 K resulted in substantial changes in the structure of the nanoclusters.