Second-Order Quadrupole Shifts ofBr81in KBr Doped with NaBr

Weak resolved second-order quadrupole-shifted satellite lines of ${\mathrm{Br}}^{81}$ in KBr doped with NaBr have been studied and ascribed to ${\mathrm{Br}}^{-}$ ions at sites similar to (102) with respect to a ${\mathrm{Na}}^{+}$ ion and at sites similar to (101) with respect to an unintentional ${\mathrm{Cl}}^{-}$ impurity ion. For these sites values are calculated for the largest element of the field-gradient tensor in the principal-axis system, the asymmetry parameter, and the angles relating the principal-axis system to the cubic-crystal axes. A comparison with published theoretical values for these quantities is made. Simple expression for first- and second-order quadrupole shifts are presented, which are useful in analyzing many systems containing at least one reflection plane of symmetry.