Abundance ratios of mercury isotopes by 6s6p P-3(1)-intermediate state excitation with resonance ionization mass spectrometry

The isotope-selective excitation of mercury via the 6s6p P-3(1) intermediat e state excitation is studied with two-color resonance ionization mass spec trometry to determine abundance ratios of stable mercury isotopes. Lifetime , isotopic shifts, and hyperfine structure (HFS) splittings are measured. A tomic hyperfine interaction constants are determined. Line strengths of the ten components of the 6s(2) S-1(0) --> 6s6p P-3(1) transition are used for isotope ratio determinations. Ion signal intensities of even-mass componen ts directly give the isotopic abundance, in contrast to the odd-mass compon ents, for which the sum of the HFS components results in an anomalously hig h response for the isotopic abundance. The laser bandwidth dependence of th e excitation and population probabilities of magnetic HFS sublevels due to linear polarization of the radiation are discussed. These considerations yi eld reasonable values for the apparent odd-mass isotope abundance.