Abstract

The ethoxy (C₂H₅O) radical is an important chemical intermediate in combustion and atmospheric reactions.¹ It belongs to the C_s point group and has 18 normal vibrational frequencies.² Four vibrational frequencies have been reported earlier,³ but only one— the CO stretch—has been assigned definitively. The C₂H₅O radical was generated in situ by photolyzing ethyl nitrite (C₂H₅ONO) with K_rF (at 248 nm) excimerlaser pulses. The nitrite precursor (at 1% concentration) was transported by helium under high pressure (12–14 atm) and was seeded into the vacuum chamber in the form of a supersonic molecular beam through a commercial pulsed nozzle. We have recorded laser-excitation spectra of jet- coofecf C₂H₅O with 0.15-cm⁻¹ resolution, and we have obtained dispersed fluorescence spectra with the aid of a 0.275-m monochromator (equipped with a 300- grooves/mm grating of 1-nm resolution). A frequency-doubled Nd:YAG-pumped dye laser with a nominal linewidth of 0.07 cm⁻¹ served as the probe beam. Optogalvanic transitions excited by using a commercial F_e-N_e hollow-cathode discharge lamp were used to calibrate the wavelength of the dye laser. The radicals were excited downstream in the jet expansion, and the delay between the photolysis and excitation beams was typically 8 μs.

© 1995 Optical Society of America