<title>Some molecular ions of astrophysical importance: the infrared spectroscopy of H3+ and carbo-cations</title>

Abstract

We continue to perform high resolution infrared spectroscopic studies on the vibration-rotation spectra of small polyatomic cations: H3+, CmHn+, HmOn+, and NmHn+, (m,n >= 1). All these ions have been proposed as having fundamental roles in the chemistry of interstellar molecular gas clouds, the birthplace of stars. In particular, H3+ plays the part of the universal protonator: H3+ + X yields H2 + HX+. The work horse of our high resolution molecular ion spectroscopy has been our difference-frequency laser spectrometer with its tunable infrared source. The molecular ions are made in a Pyrex multiple-inlet-multiple-outlet discharge cell using a gas mixture with a high fraction of He (approximately 95%) and various types of cooling (air, water, and liquid nitrogen). The ion signals are detected by velocity modulation of the plasma with unidirectional multipassing and noise subtraction of the probing infrared radiation. This spectrometer has been used for our studies of the vibration-rotation spectra of H3+ fundamental, overtone and hot bands, and of CH2+, CH3+, C2H2+ and C2H3+ fundamental bands. Most recently, we have used a water cooled, Cu hollow cathode discharge to re-examine C2H3+.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.