Small signal gain and vibrational relaxation for 13 CO 2

We have determined the small signal gain for the P(18) transition of the 13CO2 and 12CO2 isotopes for identical pumping conditions in an x-ray preionized discharge amplifier. We have also determined vibrational–relaxation rate constants for He, N2, and 13CO2 from the decay of the small signal gain on the P(18) transition of 13CO2 in the same x-ray preionized discharge amplifier. The vibrational–relaxation rate constants for N2 and 13CO2 on the 13CO2P(18) transition at 11.1 μm are a factor of 3 faster than the corresponding rate constants for the 12CO2 isotope.