A reference compound for 199mHg perturbed angular correlation of γ-rays spectroscopy

199mHg is a very useful probe for perturbed angular correlation of γ-rays (PAC) spectroscopy. Here we present 199mHg PAC data for a Hg2+ containing compound, Hg(Cys)2(s), giving one unique nuclear quadrupole interaction (NQI). Four separate sample preparations were carried out, and measured on analogue and digital PAC setups, leading to the following reference data: νQ=1.458(7) GHz and η=0.10(6). The compound may be applied as an easy-to-synthesize reference sample, providing fast control of the effective anisotropy and time calibration of PAC instruments to be used for 199mHg PAC experiments.