PerspectiveChemistry

Taking the Pulse of Molecular Rotational Spectroscopy

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Science  19 Aug 2011:
Vol. 333, Issue 6045, pp. 947-948
DOI: 10.1126/science.1207994

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Summary

Molecular rotational spectroscopy is the most incisive tool available for structure determination of gas-phase molecules. Even small changes in the distances between atoms or in their mass (different isotopes) alter their rotational spectrum in predictable and measurable ways (1). Much as an ice skater spins faster or slower by changing posture, structural changes alter how a molecule rotates. For some molecules, there can be an embarrassment of riches—the natural occurrence of many different isotope combinations (isotopomers) leads to complex overlapping spectra. On page 1011 of this issue, Schröter et al. (2) report a method for sorting out these spectra by coupling rotational spectroscopy with mass spectrometry through the use of ultrafast laser pulses. The result is a technique with impressive sensitivity and broad applicability.