We will discuss a versatile new instrument developed in our group for the measurement of rovibrational transitions of astrochemically important molecular ions with sub-MHz accuracy and precision.  A liquid-nitrogen cooled positive column discharge cell is probed with sub-Doppler spectroscopy performed with a high-power optical parametric oscillator locked to a moderate finesse external cavity.  Our approach uses frequency modulation (heterodyne) spectroscopy to reduce noise, and velocity modulation to enable ion-neutral discrimination.  Lamb dips are calibrated using an optical frequency comb.  This technique is completely general as it relies on the direct measurement of absorption or dispersion of rovibrational transitions.  We will present proof-of-concept measurements of H3+, HCO+, and CH5+, and discuss how future results from this instrument will support astronomical observations of interstellar molecular ions.

High-precision and high-accuracy rovibrational spectroscopy of astrochemically important molecular ions

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.