Infrared Spectroscopy using Difference Frequency Generation in AgGaS2: Propargyl Radical

The propargyl radical (HCCCH2) is of interest as a possible precursor in benzene and soot formation in flames and as one of the simplest conjugated organic free radicals. Because of its importance, several spectroscopic investigations of this species have recently been carried out.1-4 In order to learn more about its structure and potential surface, we have begun an investigation of the high resolution infrared spectra of the partially deuterated form, DCCCH2 in the region of the CD stretching fundamental. In this work an infrared kinetic spectroscopy apparatus5 based on difference frequency generation in the nonlinear material AgGaS2 was employed.