Dipole and Quadrupole Moments of the IsomericHg197*Nucleus; Isomeric Isotope Shift

Abstract

The hyperfine structures of five optical lines of 65-hour radioactive ${\mathrm{Hg}}^{197}$ and 25-hour isomeric ${\mathrm{Hg}}^{197*}$ were measured. Radioactive mercury produced by cyclotron bombardment and excited in electrodeless discharge tubes containing as few as 5×${10}^{12}$ atoms, free of natural mercury, gave adequate light intensities. The analysis of the hyperfine structure confirmed the magnetic dipole moment and isotope shift of ${\mathrm{Hg}}^{197}$ in its ground state ($I=\frac{1}{2}$), and gave the following values for ${\mathrm{Hg}}^{197*}$ $(\mathrm{based}\mathrm{on}I=\frac{13}{2}):{\mu }_{{197}^{*}}=-1.04\mathrm{}\pm 0.01$ nm; $Q_{{197}^{*}}=(1.5\mathrm{}\pm 0.3)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$; isotope shift displacement (from ${\mathrm{Hg}}^{198}$ in the 2537 A line)+70±7×${10}^{-3\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. Thus an isomeric shift of atomic energy levels resulting from the excitation of the nucleus from its ground state $I=\frac{1}{2}$ to the isomeric state $I=\frac{13}{2}$ is observed. In the 2537 A line of mercury this shift amounts to -21±6×${10}^{-3\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$.