Electron Spin Resonance Studies of Nitrogen Atoms Stabilized in Impurity-Helium Condensates

Abstract

Impurity-helium condensates (IHCs) created by injection of nitrogen atoms and molecules as well as rare gas (RG) atoms (Ne, Ar, and Kr) into superfluid $$^4$$ He have been studied via electron spin resonance (ESR) techniques. We investigated the influence of addition of rare gas atoms (Ne, Ar, and Kr) into the condensing $$\hbox {N}_2$$ –He gas mixture on the efficiency of stabilization as well as on the local and average concentrations of N atoms attainable in IHCs. Addition of Ar and Kr atoms into the condensing $$\hbox {N}_2$$ –He gas mixture substantially increased the stabilization efficiency of N atoms in nanoclusters forming IHCs. Measurements of the ground-state spectroscopic parameters of nitrogen atoms show that the nanoclusters have a shell structure. Most of the N atoms reside on solid molecular layers of $$\hbox {N}_2$$ . These layers form on the surfaces of RG (Ar or Kr) nanoclusters.