Spectral hole-burning study of hyperfine and nuclear quadrupole interactions ofAm3+243inCaWO4

Abstract

An optical spectral hole-burning technique has been used in study of the hyperfine and nuclear quadrupole interactions of $^{243}\mathrm{Am}^{3+}$ in ${\mathrm{CaWO}}_{4}$. Previous work on $^{243}\mathrm{Am}^{3+}$ in ${\mathrm{LaCl}}_{3}$ [Phys. Rev. B 53, 2385 (1996)] provided an analysis of the nuclear quadrupole interaction in the $^{7}\mathrm{F}_{0}$ ground state and predicted an anomalous nuclear quadrupole interaction in the optically excited state $^{5}\mathrm{D}_{1}$. In the present work on $^{243}\mathrm{Am}^{3+}$ doped into ${\mathrm{CaWO}}_{4}$, hyperfine energy levels in both the $^{7}\mathrm{F}_{0}$ ground state and the $^{5}\mathrm{D}_{1}$ excited state of an $^{243}\mathrm{Am}^{3+}$ ion have been resolved in spectral hole-burning experiments. A theoretical analysis is reported for the hyperfine and nuclear quadrupole interactions in the non-Kramers doublet of the $^{5}\mathrm{D}_{1}$ excited state of $^{243}\mathrm{Am}^{3+}$ in ${\mathrm{CaWO}}_{4}$. Whereas the crystal-field antishielding effect dominates the ground state nuclear quadrupole splitting, a first order electronic hyperfine interaction dominates the excited state splitting. It is shown that the contribution from the nuclear electric quadrupole interactions in the $^{5}\mathrm{D}_{1}$ excited state is much smaller than that in the $^{7}\mathrm{F}_{0}$ ground state, because the first order nuclear quadrupole interaction with the 5f electrons is canceled in part by the contribution from the lattice interaction.