Michio MATSUSHITA and Tatsuhisa KATO
[Chem. Phys. Lett. 273, 291 (1997)]
The nuclear quadrupole transitions of 139La around Pr3+ doped in LaF3 have been detected as an optical-rf induced coherent Raman beat on the Pr3+ 3H4 - 3P0 transition (20925 cm-1) at 1.5 K. Because the effective 141Pr nuclear magnetic moment is smaller in the excited 3P0 state than in the ground state, the Pr - La interaction decreases upon Pr3+ optical excitation, which makes the La NQR transitions couple with the Pr optical transition. Four magnetically inequivalent La nuclei were observed, revealing different local environments of La atoms around impurity Pr3+ ions.
Figure 1. Raman heterodyne detected NQR of La around Pr3+ in LaF3 at 1.5 K. Labels (alpha) through (delta) assign the transitions to four different nearest neighbour La sites around Pr3+. A forbidden (DELTA)MI = 2 transition is observed for sites (alpha), (beta), and (gamma). The NQR frequencies of bulk La at 88 K are also indicated in the figure.