Raman cross sections measured by short-pulse laser scattering and photon counting

Using a repetitively pulsed nitrogen laser of 100-kW peak power and 10-nsec duration, the Raman scattering cross sections at 3371 Å for various gas species relative to that of molecular nitrogen have been measured by a gated photon counting technique. The gases studied include N2, O2, CO, CO2, NO, SO2, C3H6, and C3H8. A statistical correction formula has been derived and applied to the apparent count rate to avoid possible errors due to the finite recovery time of the counter and its inability to distinguish between single- and multiple-photon arrival events within the very short time gate. The resultant accuracy of the present measurements is accordingly estimated to be better than ± 5%.