Vibrational relaxation of N2 by H2O

The vibrational relaxation of N2 by H2O has been measured behind incident shock waves in the temperature range from 1600 to 3100 °K. The H2O concentration was measured with a calibrated capacitance hygrometer. The vibrational relaxation was monitored by redundant diagnostics: interferometric measurements of the gas density and infrared emission measurements of the CO fundamental band using CO as a tracer species to reflect the N2 vibrational energy. The experimental results support the slowest published measurements of von Rosenberg et al. Taken together with existing low-temperature data, the deactivation of N2 by H2O can be expressed in the form pτN2–H2O=exp(21T−1/3−1.35) μsec-atm.