Vibrational relaxation of N2 by H2O

Abstract

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 pτ_N2–H2O=exp(21T^−1/3−1.35) μsec‐atm.