JET-COOLED, BROAD RANGE NEAR-IR SCAN OF REACTIVE INTERMEDIATES USING CAVITY RINGDOWN SPECTROSCOPY

Author Institution: Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210.Ming-Wei Chen present address: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801A technique has been developed for obtaining broad range scans of jet-cooled radicals using cavity ringdown spectroscopy. The talk will describe a method that uses a slit jet expansion in tandem with an electrical discharge to produce the reactive intermediates and obtain rotational temperatures of 15-30 K and effective vibrational temperatures of 0 K. The spectrum can be recorded by scanning the second stokes of an H$_2$ Raman shifted YAG-pumped dye laser with bandwidth of $\approx$ 0.1 cm$^{-1}$. This technique has been used to obtain the jet-cooled $\widetilde{A} - \widetilde{X}$ spectra of the NO$_3$ radical and the 2,1-hydroxypropyl peroxy radical (2,1-HPP). Obtaining the jet-cooled spectra helped to identify hot bands present in the room temperature spectrum of NO$_3$ and also helped to identify cold, low-frequency fundamental bands present in the 2,1-HPP spectrum