Determination of optical interband transitions in crystalline quartz from X‐ray spectroscopical data

For the interpretation of the imaginary part ε2(ω) of the dielectric constant of a solid usually determined from the optical spectra, one can successfully use X‐ray emission spectra and the near‐edge region of X‐ray absorption spectra. This is shown in the case of crystalline quartz. From the X‐ray spectra of this substance conclusions are drawn about the density of states in the valence and conduction band. The possible vertical interband transitions resulting from these conclusions agree very well with maxima in the transition strength ε2(ω) ω2 determined from optical measurements. Furthermore it is demonstrated that the sharp peak at 10.4 eV must be due to an exciton transition in agreement with conclusions drawn from the optical spectra.