Hyperfine Structure and Nuclear Moments of the Stable Bromine Isotopes

Abstract

The hyperfine structure of the $^{2}P_{\frac{3}{2}}$ state of atomic ${\mathrm{Br}}^{79}$ and ${\mathrm{Br}}^{81}$ has been investigated by the atomic-beam, magnetic-resonance method. The following values have been obtained for the nuclear magnetic dipole interaction constant, $a$, and the nuclear electric quadrupole interaction constant, $b$: ${a}^{79}=884.810\ifmmode\pm\else\textpm\fi{}0.003 \mathrm{Mc}/sec, {a}^{81}=953.770\ifmmode\pm\else\textpm\fi{}0.003 \mathrm{Mc}/sec,$ ${b}^{79}=\ensuremath{-}384.878\ifmmode\pm\else\textpm\fi{}0.008 \mathrm{Mc}/sec, {b}^{81}=\ensuremath{-}321.516\ifmmode\pm\else\textpm\fi{}0.008 \mathrm{Mc}/sec.$From these data, an upper limit of 0.0001 Mc/sec can be placed on the nuclear magnetic octupole interaction constant, $c$. Applying the results of recent theoretical calculations by Sternheimer and Koster, the following values of the nuclear quadrupole moments were computed: ${Q}^{79}=(0.33\ifmmode\pm\else\textpm\fi{}0.02)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24} {\mathrm{cm}}^{2}, {Q}^{81}=(0.28\ifmmode\pm\else\textpm\fi{}0.02)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24} {\mathrm{cm}}^{2}.$ The ratios ($\frac{{a}^{79}}{{a}^{81}}$) and ($\frac{{b}^{79}}{{b}^{81}}$) are in satisfactory agreement with the ratios ($\frac{{\ensuremath{\mu}}^{79}}{{\ensuremath{\mu}}^{81}}$) and ($\frac{\mathrm{eq}{Q}^{79}}{\mathrm{eq}{Q}^{81}}$), respectively, as measured by other methods.An experimental technique is given for combining many of the advantages of the "flop-out" resonance method with those of the "flop-in" resonance method in the analysis of complex spectra.Increased importance can be assigned to the hyperfine structure interaction constants of pairs of isotopes in view of the available information on the ground states of nuclei and on nuclear structure, and the fact that new methods exist for precise measurements of the ratio of nuclear moments.