Abstract

We have developed a continuously tunable, high brightness, high resolution spectrometer for obtaining infrared spectra and kinetic information for free radicals. This source is based on difference frequency mixing of two single frequency visible lasers in AgGaS₂ using type I non-critical phasematching. We have previously demonstrated that our spectrometer extends the advantages of difference frequency generation spectroscopy into the 4-9 µm (2500 -1100 cm^-1) portion of the infrared fingerprint region.¹² Improvements in the infrared power output, the multipass absorption cell, and the experimental geometry have now enabled us to record the first free radical spectra with this spectrometer. The ν₂ C=O stretching fundamental of HOCO was observed in the 1862 cm^-1 region3 and portions of the the ν₂ CCN antisymmetric stretching vibration of HCCN have been found near the 1740 cm^-1 value predicted from matrix isolation studies.4 The implications of the CCN antisymmetric stretching motion on the question of quasi-linearity in HCCN will be addressed.

© 1993 Optical Society of America