Nuclear Quadrupole Resonance ofHg201

Abstract

Five nuclear quadrupole resonance lines have been observed in polycrystalline Hg${\mathrm{Cl}}_2$. From their frequencies, the magnitudes of the quadrupole coupling constants $\mathrm{eQ}{q}_{\mathrm{zz}}\left({\mathrm{Hg}}^{201}\right)=720\mathrm{}$ Mc/sec and $\mathrm{eQ}{q}_{\mathrm{zz}}\left({\mathrm{Cl}}^{35}\right)=44.3\mathrm{}$ Mc/sec were evaluated. Comparison of the ${\mathrm{Cl}}^{35}$ coupling constant in Hg${\mathrm{Cl}}_2$ with that known for the free Cl atom from atomic beam experiments facilitates the discussion of the molecular structure. A quadrupole coupling constant of 1000 Mc/sec per $p$ electron in the $6s6p$ configuration of free Hg is deduced from the ${\mathrm{Hg}}^{201}$ coupling in Hg${\mathrm{Cl}}_2$. This value can be directly compared with the coupling of the $6s6p$, ${}_{}{}^2{}_{}{}^{}P_2^{}{}_{}{}^{}$ HgI term, $\mathrm{eQ}{q}_{\mathrm{zz}}({\mathrm{Hg}}^{201}, p_z)=780\mathrm{}$ Mc/sec, which is equivalent to the value of the quadrupole parameter $B=0.27\mathrm{}\times {10}^{-3\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ known from optical hfs investigations. Whereas a standard analysis of the hfs of the ${}_{}{}^2{}_{}{}^{}P_2^{}{}_{}{}^{}$ term had given $Q\left({\mathrm{Hg}}^{201}\right)=0.5\mathrm{}\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$, a discrepant value $Q\left({\mathrm{Hg}}^{201}\right)=0.2\mathrm{}\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ was obtained from the ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ term. Our results yield a value 0.6×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$, in fair agreement with the larger value found for the ${}_{}{}^2{}_{}{}^{}P_2^{}{}_{}{}^{}$ term.