Temperature and pressure dependence of NH_3 and C_2H_4 absorption cross sections at CO_2 laser wavelengths

Absorption cross sections at CO(2) laser wavelengths have been measured for ethylene and ammonia. The dependence of the cross sections on pressure and temperature have been investigated for pressures and temperatures normally occurring in the atmosphere. The changes in cross section are, e.g., 5% for ethylene at the P(14) 00 degrees 1-10 degrees 0 line and 10% for ammonia at the R(8) 00 degrees 1-10 degrees 0 line for a temperature change of 30 K. A comparison with theoretical calculations is made for ammonia.