Electron-spin-resonance study of Tl atom defects in KCl and relativistic many-body analysis of the hyperfine structure

摘要: Two thallium atom defects of tetragonal symmetry around $〈100〉$ are produced by x irradiation above 230 K in KCl: TlCl. Their electron-spin-resonance spectra characterized comparable and large $g$ shifts but quite different hyperfine parameters. A relativistic many-body calculation the ${\mathrm{Tl}}^{0}$ interaction including effect a crystal field permits quantitative analysis spin-Hamiltonian It is found particular that data two can be explained assuming presence one or perturbing positive charges, respectively, corresponding 35 45% delocalization $6{p}^{1}$ electron on surrounding lattice. This together with x-ray production, optical-excitation, pulse-anneal fact both only at temperatures where negative-ion vacancies mobile (g230 K) allows to propose precise defect structures: In (on positive-ion site) associated single vacancy nearest-neighbor position along $〈100〉$; other one, flanked $〈100〉$. The also provide strong evidence for existence consisting ${\mathrm{Tl}}^{+}$ ion anion vacancy.