RADIATION ABSORPTION BY THE 020(550)-]001(633) TRANSITION OF H2O BEHIND SHOCK-WAVES

Measured results are presented for absorption of 27.971-mu-m laser radiation by water vapour heated by an incident shock wave in a shock tube for 900 less-than-or-equal-to T, K less-than-or-equal-to 2300 and 6 less-than-or-equal-to p, kPa less-than-or-equal-to 70. The effects of the boundary layer and vapour condensation on absorption have been analysed. Comparisons of experimental and calculated results lead to values of 2 sec-1 and 0.45 cm-1 atm-1 for the Einstein coefficient A(mn) for the 020(5(50))-->001(6(33)) transition and the collisional broadening coefficient gamma(c)020-->001, respectively. Also, gamma(c)020-->001(T) is similar to T-0.62. For pure-rotation transitions, 0.6 less-than-or-equal-to gamma(c), cm-1 atm-1 less-than-or-equal-to 0.8.