Hyperfine sublevel correlation spectroscopy in lithium silicate glasses

The structure of γ-irradiated (Li2O)0.1(SiO2)0.9 glass has been studied with two-dimensional hyperfine sublevel correlation spectroscopy (HYSCORE). The theoretical evaluation of the HYSCORE experimental data revealed the existence of weak couplings between the electron spin and nearby Li. The anisotropic hyperfine coupling T is equal to 4.0 MHz suggesting a nonbridging oxygen—Li distance of 2.0 A and an angle of ±60° away from the gz axis. The Aiso value is equal to 0.5 MHz, corresponding to 0.135% contribution of the Li 2s orbital to the ground state. Thus, an estimation can be made of the covalent character of the bond between the nonbridging oxygen and the alkali.