Abundance ratios of mercury isotopes by 6 s 6 p 3 P 1 -intermediate state excitation with resonance ionization mass spectrometry

Abstract

The isotope-selective excitation of mercury via the 6s6p3P1 intermediate state excitation is studied with two-color resonance ionization mass spectrometry to determine abundance ratios of stable mercury isotopes. Lifetime, isotopic shifts, and hyperfine structure (HFS) splittings are measured. Atomic hyperfine interaction constants are determined. Line strengths of the ten components of the 6s21S0→ 6s6p3P1 transition are used for isotope ratio determinations. Ion signal intensities of even-mass components directly give the isotopic abundance, in contrast to the odd-mass components, for which the sum of the HFS components results in an anomalously high response for the isotopic abundance. The laser bandwidth dependence of the excitation and population probabilities of magnetic HFS sublevels due to linear polarization of the radiation are discussed. These considerations yield reasonable values for the apparent odd-mass isotope abundance.