NUCLEAR-SPIN OF BI-207 BY LASER ZEEMAN SPECTROSCOPY

Laser spectroscopy has been used to obtain a definitive nuclear spin a ssignment, I = 9/2, for 31.5-y Bi-207. For such a large spin the value obtained from previous hfs measurements at zero magnetic field was su bject to uncertainty. The Zeeman pattern of the 6p3 4S3/2 - 6p(2)7s 4P 1/2 306.7-nm resonance line was studied at a magnetic field of almost- equal-to 0.75T to yield the result. The spectrum was detected by the o bservation of the 6p(2)7s 4P1/2 - 6p3 2D3/2 fluorescence at 472.2 nm. A comparison of Doppler-broadened spectra obtained by laser-excited fl uorescence spectroscopy and those by dispersive spectroscopy put in ev idence the additional effect of the diffraction-grating instrument fun ction.