Abstract
Low-temperature x-irradiation of high-purity Ge-doped quartz leads to a broad absorption peaked at 2.25 eV, typical of small hole polarons bound at oxygen sites, and to absorption at 4.2 eV due to Ge3+. The annealing behaviour of the polaron band parallels that of the ESR of the recently discovered H(I/II/III) hole centres trapped near Ge sites. These hole centres are similar to the well known AlSi0 hole centre and their properties are compared.