Knowledge Bank

“Several optical absorption bands of $\alpha$-quartz at wavelengths near 3 $\mu$ have been studied in both natural and synthetic crystals. These bands can be attributed to electronic transitions. Their appearance, which depends on the origin of the crystal, can be modified by low temperatures, x-irradiation. electro-diffusion of ions within the lattice, and annealing. The origin of the bands will be discussed in terms of the energy levels associated with defects and impurity centers in the lattice, and a tentative interpretation of the spectra will be given.”