Hyperfine spectra of the radioactive isotopesKr81andKr85

Isotope shifts and hyperfine constants are reported for the radioactive isotopes ${\mathrm{Kr}}^{81}$ and ${\mathrm{Kr}}^{85}$ and the stable isotope ${\mathrm{Kr}}^{83}$. The previously unreported nuclear moments of ${\mathrm{Kr}}^{81}$ were determined to be ${\mathrm{\mu }}_{\mathrm{I}}$=-0.909(4) nuclear magneton and Q=+0.630(13) b from the hyperfine constants. This work increases the number of transitions for which ${\mathrm{Kr}}^{85}$ hyperfine constants and isotope shifts have been measured from 1 to 4. The hyperfine anomaly for krypton reported in the previous measurement of ${\mathrm{Kr}}^{85}$ hyperfine constants [H. Gerhardt et al., Hyperfine Interact. 9, 175 (1981)] is not supported by this work. The isotope shifts and hyperfine constants of ${\mathrm{Kr}}^{83}$ measured in this work are in excellent agreement with previous work. Saturation spectroscopy was used to study transitions from krypton's metastable ${1\mathrm{s}}_5$ state to the ${2\mathrm{p}}_9$, ${2\mathrm{p}}_7$, and ${2\mathrm{p}}_6$ states. In saturation spectra, different line shapes were observed for the even- and odd-mass krypton isotopes. This even- versus odd-line-mass shape difference can be explained using the large cross section that has been reported for collisional transfer of the ${1\mathrm{s}}_5$ state excitation between krypton atoms. Two-color two-photon laser-induced fluorescence was used to measure the hyperfine spectra of the ${1\mathrm{s}}_5$-${4\mathrm{d}}_4^{\prime }$ transition using the ${2\mathrm{p}}_9$ state as the intermediate state. This technique proved to be more sensitive than saturation spectroscopy.