Radiolysis of NO with a 30hyphen;nsec pulse of 2hyphen;MV electrons produces absorption bands attributed to NO2, N2O3, and vibrationally excited NO. In pure NO at 1 atm, most of the NO2forms during the pulse, but the formation of N2O3is slowerlpar;tgr;thinsp;equals;thinsp;0.3 mgr;secrpar;. The NO2is produced by the reaction of O atoms with NO, and the pseudohyphen;firsthyphen;order rate constant for formation of NO2in an 11percnt; NOsngbnd;Ar mixture is slightly lower than that calculated from published values. The N2O3comes from the equilibrium NO2thinsp;plus;thinsp;NOlrarr2;N2O3, which is achieved in 1 mgr;sec, orders of magnitude faster than the previously estimated lower limit. The sum of yields of the two products (10.6thinsp;plusmn;thinsp;0.5 molecules/100 eV) was independent of the pulse dose, but the ratioG(NO2)thinsp;/thinsp;G(N2O3) increased with dose. This can be explained by a shift in the above equilibrium caused by the temperature increase produced by the pulse. Superimposed on the broad N2O3band in the ultraviolet was a sharp band at 2362 Aring;, indicating population of the first vibrational level of NO. The relaxation lifetime was 5.8 mgr;sec for 13percnt; NO in Ar and 1.6 mgr;sec for 41percnt; NO, giving a quenching probability by NO of 2.1thinsp;plusmn;thinsp;0.2thinsp;times;thinsp;10minus;4compared with 3.6thinsp;plusmn;thinsp;0.4thinsp;times;thinsp;10minus;4reported by Basco, Callear, and Norrish. A small amount of absorption in the (0, 2) band at 2472 Aring; decayed with a lifetime sim;1.4 mgr;sec, giving a probability for resonant vibrationndash;vibration exchange of only sim;10minus;3.
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