HIGH-RESOLUTION COHERENT ANTI-STOKES-RAMAN SPECTROSCOPY OF ETHANE

A continuous-wave CARS spectrometer was equipped with a new frequency- stabilized argon ion ring laser and better stabilization for the tunab le dye laser was introduced. Special quartz sample cells with Brewster angle windows were placed in the focal region of the argon ion ring l aser. A new data acquisition system was installed which allows the sim ultaneous recording of CARS signals and calibration spectra and the su bsequent evaluation of the data An instrumental resolution of less tha n 0.001 cm(-1) and a wavenumber accuracy of about +/- 0.006 cm(-1) wer e achieved. As an example of the performance of the spectrometer, the CARS spectrum of ethane was measured in the region of the CH vibration s at pressures between 95 and 1.9 kPa. The spectra were compared with the stimulated Raman spectrum published recently.