A Study of the Collisional Activation of Cyclobutanone by the Transient Heating of SiF4

Article abstract of DOI:10.1021/j150653a035

The unimolecular decomposition of cyclobutanone has been used to study the behavior of SiF4 as a heat bath gas.Temperatures in the neighborhood of 1050 K were obtained by rapid flow through a heated tube and by the absorption of the pulsed infrared radiation emitted by a CO2 TEA laser tuned to 1033 cm^-1.The effective reaction times of these two heating methods were approximately 1 ms and 100μs, respectively.The two separate decomposition channels of cyclobutanone were studied by a comparative method that is insensitive to the nonuniform temperatures inherent in all transiet heating methods.It was shown that, between 5 and 30 torr, both channels are in the unimolecular falloff regime.Further at laser fluences greater than 0.5 J/cm², a third higher activation energy channel is opened with effective reaction times that are less than 10 μs.Times of this magnitude are too small for complete equipartition of the vibrational energy deposited in the heat bath and hence involves rapid v-v energy transfer to the cyclobutanone resulting in its excitation to near 300 kJ/mol and provides access to the third reaction channel.