CARS spectrometer with cw intra‐cavity excitation for high‐resolution Raman spectroscopy

The construction of a cw CARS spectrometer is described, consisting of a single mode argon ion ring laser, an intra-cavity sample cell and a tunable dye laser. The argon laser was first stabilized to an iodine absorption line. From an evaluation of the CARS spectrum of the Q-branch of the rovibrational band of nitrogen, the vibration-rotation interaction constant is obtained as αe = 0.0173850 ± 0.0000035 cm−1, in agreement with Bensten's result from the linear Raman spectrum of the total band. Finally, the stabilization of the argon laser to a hyperfine component in the Doppler-free polarization spectrum of iodine is described.