Absorption Spectra and Energy Levels of Gd(3+), Nd(3+), and Cr(3+) in the Garnet Gd3Sc2Ga3O12

摘要

Absorption spectra recorded between 0.3 and 6.7 micro are reported for trivalent gadolinium, trivalent neodymium, and trivalent chromium in single-crystal gadolinium scandium gallium garnet, Gd3Sc2Ga3O12, at liquid nitrogen, and room temperatures. Crystalline electric-field-split energy levels are established from data between 1,5000 and 35,000/cm for Gd3+ (4f7), Nd3+ (4f3), and cr3+ (3d3). The Gd3+ and Nd3+ ions occupy sites having D2 point symmetry; Cr3+ ions are found primarily in sites of C3i point symmetry. A Hamiltonian consisting of Coulombic, spin-orbit, and crystalline electric-field terms, having symmetry appropriate to each ion, is diagonalized to obtain theoretic energy levels. The rms deviation between calculated and observed levels for Nd3+ (with 45 levels) is 1.7/cm, for Gd3+ (with 14 levels) is 4/cm, and for Cr3+ (with 35 levels) is 87.7/cm. A lattice su, calculation is compared with the phenomenological parameters obtained from fitting the observed energy levels.