Effect of Pressure on the Spectra of Color Centers

Abstract

The effect of pressure on the spectra of certain color centers produced in the alkali halides by x irradiation has been measured to pressures as high as 166 000 atm. For the F center a shift to higher energies with increasing pressure is observed. The slope of the shift versus density is at least twice the value that would be predicted from Ivey's relation at low pressure, and decreases with increasing pressure. This indicates that the compressibility in the neighborhood of the F center is greater than in the bulk crystal, particularly at low pressure. For the M center in LiCl a shift to higher energy with increasing pressure is observed, about one‐fifth as great as the shift observed for the F center.