Time Behavior of CN Radicals in Laser-Initiated Thermal Isomerization of CH₃NC

Abstract

Using techniques of laser induced fluorescence (LIF) applied earlier in a study of i.r. laser induced photodissociation of CH₃CN[1], we have studied the time behavior of CN radicals resulting from the application of single pulses of focused CO₂ TEA laser radiation in CH₃NC vapor, at pressures both above[2] and below[3] the threshold for thermal explosion. For comparison, observations were also made in CH₃CN vapor. The results are of interest in that they appear to rule out the importance of a CN-catalyzed isomerization route

$$ {\text{CN + C}}{{\text{H}}_{{\text{30}}}}{\text{NC}} \to {\text{C}}{{\text{H}}_{\text{3}}}{\text{CN + CN}}$$

((1))

proposed earlier [4] as an alternative mechanism for the CH₃NC→ CH₃CN isomerization. The latter has been generally regarded as a model unimolecular reaction.