Effect of Pressure on the Spectrum of Ruby

Abstract

The effect of pressure has been measured on the spectrum of ruby, both parallel and perpendicular to the C axis, to 120 kbar. From these data it is possible to calculate the change in crystal field strength D_q in interelectronic repulsion B and in trigonal field distortion ($-\frac{3}{2}K$ ). The crystal field increases with increasing pressure, while the interelectronic repulsion decreases, indicating increasing covalency. The trigonal distortion is constant to about 60 kbar, and then increases markedly at higher pressures. The fractional change in D_q with pressure follows the R^‐5 law closely to 30 kbar, the upper limit of the p‐v data.