Effect of Pressure on the Spectra of Rare Earth Ions in Crystals

Abstract

The effect of pressure to 180 000 atm has been measured on the absorption spectra of crystalline rare earth ions. The effects observed include: (1) An increase of intensity due to increased mixing of 5d and 4f orbitals in the excited state due to an increase of the mixing potential with decreased interionic distance. (2) Small shifts accompanied by increases in half‐width. Except for the shifts of ³P₀, ³P₁, and ³P₂ levels of Pr⁺³, these can be accounted for by an increase in the splitting of the individual levels due to intensification of the crystal field. (3) Changes in shape of several of the bands, possibly due to changes in occupation of the various states which make up the bands.