ABSOLUTE SIGN DETERMINATION OF NUCLEAR-QUADRUPOLE COUPLINGS BY LASER-RADIOFREQUENCY DOUBLE-RESONANCE

The combination of optical and radio frequency is a well-known techniq ue for obtaining spectra of nuclear quadrupole transitions with high r esolution and high sensitivity. A new and attractive feature of this t echnique is, that it allows not only the determination of the strength and orientation of the quadrupole- and Zeeman tensors, but also of th e absolute sign of the nuclear quadrupole interaction. This determinat ion of the sign, which is essential for the comparison with calculated EFG tensors, is not possible with purely magnetic methods.