Germanium-Hydrogen-Lithium Center in α-Quartz

Abstract

A new center, denoted by GeHLi₂, has been observed by EPR to be present in alpha‐quartz containing germanium, after room temperature x irradiation. The spin Hamiltonian at 8909 MHz and 300°K has been measured, yielding the Zeeman splitting tensor ḡ and the hyperfine coupling tensors Ā (⁷³Ge), Ā (¹H), Ā (⁷Li₁), and Ā (⁷Li₂). From the principal values and axis directions, a model for the center of the form Ge³⁺H⁻(Li⁺)₂ has been derived. This postulates germanium to be present substitutionally at a silicon site, with the hydride and two lithium ions occurring interstitially nearby. The unpaired electron is thought to be in a Ge orbital $\text{a(4s) + b(4p)}$ , with ${\mathrm{|a|}}^2\text{∼ 0.18}$ and ${\mathrm{|b|}}^2\text{∼ 0.35}$ , with considerable spin density also at the hydrogen. The center may be formed from a diamagnetic precursor Ge²⁺(Li⁺)₂ by reaction with a hydrogen atom.