Measurement of sulfur isotope compositions by tunable laser spectroscopy of SO2

Sulfur isotope measurements offer comprehensive information on the origin and history of natural materials. Tunable laser spectroscopy is a powerful analytical technique for isotope analysis that has proven itself readily adaptable for in situ terrestrial and planetary measurements. Measurements of delta S-34 in SO2 were made using tunable laser spectroscopy of combusted gas samples from six sulfur-bearing solids with delta S-34 ranging from -34 to +22%o (also measured with mass spectrometry). Standard deviation between laser and mass spectrometer measurements was 3.7 parts per thousand for sample sizes of 200 75 nmol SO2. Although SO2(g) decreased 9% over 15 min upon entrainment in the analysis cell from wall uptake, observed fractionation was insignificant (+0.2 +/- 0.6 parts per thousand). We also describe a strong, distinct (SO2)-S-33 rovibrational transition in the same spectral region, which may enable simultaneous delta S-34 and Delta S-33 measurements.