Heinz Haas

The existing experimental data for the temperature dependence of the nuclear quadrupole interaction in Zn and Cd have been accounted for by considering reanalyzed data for structure and vibrational amplitude as a function of temperature, in combination with density functional calculations of the electric-field gradient (EFG) variation due to the structure change. For Zn the complex EFG temperature effect, previously unexplained, can be fully reproduced, while for Cd it is shown that the apparent agreement with an earlier proposed universal temperature dependence as proportional to $T^{3/2}$ is due to a combination of structural and vibrational contributions. It is demonstrated that for Zn, in particular, the resulting EFG at 0 K, including the now directly calculated shift due to zero-point vibrations, and the subsequently obtained nuclear quadrupole moments, can be considerably different when taking the present revised analysis and all experimental data into account. As an additional example also one impurity system, ${}^{69}\mathrm{Ge}$ in Zn, is tentatively analyzed in this context. The possible extension of the present approach to other noncubic $s\text{−}p$ metals is envisioned.

Accurate nuclear quadrupole moment values are essential as benchmarks for nuclear structure models and for the interpretation of experimentally determined nuclear quadrupole interactions in terms of electronic and molecular structure. Here, we present a novel route to such data by combining perturbed $\gamma \text{−}\gamma$ angular correlation measurements on free small linear molecules, realized for the first time within this work, with state-of-the-art ab initio electronic structure calculations of the electric field gradient at the probe site. This approach, also feasible for a series of other cases, is applied to Hg and Cd halides, resulting in $Q({}^{199}\mathrm{Hg},5/2^{-})=+0.674(17)b$ and $Q({}^{111}\mathrm{Cd},5/2^{+})=+0.664(7)b$.