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New Spectroscopic Techniques for Astrochemistry

256th National Meeting, Boston, MA, 19 - 23 August 2018

Prof. Kyle N. Crabtree (University of California, Davis)
Dr. Michael C. McCarthy (Harvard-Smithsonian Center for Astrophysics)


Spectroscopy is a driving force behind astrochemistry. With the optical detection of CH, CH+, and CN in space in the early 1940s, astrochemistry has grown into a thriving sub-discipline of astronomy, and nearly 200 molecules, some familiar, others exotic, have now been detected beyond the Solar System; they range in size from H2, the most abundant molecule, to neutral and ionized C60. The vast majority of these detections are iron-clad because they are based on precise rest frequencies measured in the laboratory, and because approximately 90% occur in the radio band, where spectral confusion is infrequent. Spectral line measurements are an invaluable aid in probing the physical conditions and chemical evolution of a wide variety of astronomical environments, and will continue to be key in the coming years to establish if life exists on exoplanets.

The rate of new molecule detections in space shows no signs of flagging even after 75 years. Indeed, since 1970, approximately four new molecules are detected each year on average, and the recent commissioning of the Atacama Large Millimeter Array (ALMA), as well as the routine science flights of the Stratospheric Observatory for Infrared Astronomy (SOFIA), promise to match or exceed this pace for the foreseeable future. This steady and relentless rise has been driven not only by the development of astronomical facilities, but also by more innovative spectroscopic techniques in the laboratory, experimental advances in the production of possible astronomical molecules, and faster and more accurate theoretical calculations to guide experiment. In fact, given the number of unidentified spectral lines in publicly available astronomical datasets, there is every reason to expect that many more molecules exist at already detectible abundances in space, and can be found there once their spectra are measured accurately in the laboratory.

Preliminary Sessions May Include:

  • Astronomical facilities: Capabilities and recent spectroscopic results from new and existing tele- scopes.
  • Spectroscopy challenges in the interstellar medium: A discussion of spectroscopy of small molecules and their roles as probes of physical conditions of the interstellar medium. Recent observational advances on the diffuse interstellar bands, the unidentified infrared features, and polycyclic aromatic hydrocarbons.
  • Spectroscopy near new and dying stars: Observational studies in star forming regions and near evolved stars, focusing on new detections, unidentified lines, and spectroscopic needs.
  • Spectroscopy of exoplanet atmospheres: Inspired by advances in exoplanet detection and at- mosphere analysis, this session will focus on the role that spectroscopy can play and future needs.
  • Recent advances in rotational spectroscopy: Experimental developments in chirped-pulse spec- troscopy, double/triple resonance methods, and chirality detection.
  • Recent advances in optical spectroscopy: Experimental developments in such areas as fre- quency comb spectroscopy, rare gas tagging, and velocity map imaging.
  • Complex mixture analysis: New experimental methods for spectroscopic analysis of complex mixtures, especially geared toward identification of prospective astronomical molecules.
  • New techniques in molecule production: Many molecules detected in space are unstable to terrestrial conditions, and therefore require specialized techniques to enable their study in the laboratory. For this reason, a discussion of new methods is important.