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 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 -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 -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 . These layers form on the surfaces of RG (Ar or Kr) nanoclusters.