EPR study of the [SiO4/Li]0 centre in α-quartz

Abstract

The centre [SiO₄/Li]⁰ in naturally occurring crystalline rose quartz, generated during X-irradiation at 77 K and stable to ca. 10 K, has been studied in detail by single-crystal electron paramagnetic resonance (EPR) spectroscopy. The hyperfine matrices of ⁷Li and of the low-abundance isotope ²⁹Si have been measured at ca. 35 K, with [SiO₄/Li]⁰ exhibiting C₂ symmetry. The spin-population distribution within the centre has been analysed, and is found to be consistent with a previously proposed model which featured spin populations relatively low on the (almost neutral) interstitial lithium atom and high on one nearest-neighbour silicon ion.