Trapping sites of Li atom in the rare gas crystals Ar, Kr, and Xe: Analysis of stability and manifestation in the EPR spectra.

The classical model of an ideal crystal, parametrized according to non-empirical calculations, is used to determine the structure and geometry of the atomic lithium trapping sites in solid inert gases RG = Ar, Kr, and Xe, and to define their thermodynamic stability. The diversity of the observed stable sites reduces to four highly symmetric structures corresponding to the interstitial introduction of an Li atom, its substitution of an inert gas atom, or its incorporation into tetrahedral and octahedral vacancies formed by the removal of four and six inert gas atoms from the crystal lattice. The non-empirically calculated dependences of the isotropic hyperfine coupling constant tensor on the distance in the diatomic Li@RG complex are used to estimate the shifts of the electron paramagnetic resonance signals in the predicted thermodynamically stable sites. A comparison with published data does not contradict the assignment of the observed multiple signals to certain types of stable sites, taking into account the spectral features of samples that were prepared by thermal deposition and laser ablation in three different inert gases. [ABSTRACT FROM AUTHOR]