Pressure dependence of integrated CARS power

The pressure dependence of the integrated power of coherent anti-Stokes Raman scattering (CARS) has been investigated experimentally as well as theoretically. The integrated CARS power has been found to be inversely proportional to linewidth, in contrast to the spontaneous Raman scattering for which the integrated power is independent of linewidth. Because of the pressure broadening of the Raman lines and the interference among them, the integrated power deviates from a simple square-law dependence, the degree of deviation being a function of molecular species. Experimental results are presented for CH(4), CO, N(2), and H(2), with collisional narrowing being demonstrated for H(2).