Time-dependent directional correlations of /sup 199m/Hg in liquid Hg, solid Hg, and HgCl2

Time-directional correlations of the 374- and 158-keV γ rays of ${}^{199}{Hg}^m$ were studied with sources in the form of liquid Hg, frozen Hg, and dry crystalline HgCl₂. The time-dependent anisotropy in the liquid at room temperature shows no observable disturbance over several lifetimes. The integral anisotropy in the liquid indicates mixing of E5 with the predominantly M4 first γ ray with an M4/E5 mixing ratio δ=0.092±0.015. The half-life of the intermediate state was determined to be 2.47 ± 0.05 nsec. Time-dependent directional correlations in frozen emulsified Hg show a quadrupole interaction $\frac{eQ\left(\frac{{\partial }^{2}V}{\partial z^2}\right)}{h}=198\pm 40$ MHz. The time-dependent coincidence rate in HgCl₂ shows a quadrupole interaction $\frac{eQ\left(\frac{{\partial }^{2}V}{\partial z^2}\right)}{h}=1271\pm 30$ MHz. If the second γ ray is a rotational transition, the quadrupole moment of the intermediate state determined from the intermediate-state E2 lifetime can be combined with the nuclear-quadrupole-resonance frequency of ²⁰¹Hg in HgCl₂ to give a quadrupole moment for ²⁰¹Hg of 0.39 ± 0.02 b. This result is in excellent agreement with the value of 0.41 b obtained by Murakawa from the hyperfine structure of atomic mercury.