Infrared laser-induced decomposition of 2,2-dimethyloxetane

✍ Scribed by K. A. Holbrook; C. J. Shaw; G. A. Oldershaw; P. E. Dyer

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 931 KB
• Volume: 18
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550181102

✦ Synopsis

The unimolecular decomposition of 2,2 dimethyloxetane to give either isobutene and formaldehyde or ethene and acetone induced by a pulsed C 0 2 laser has been investigated. Absorption characteristics and fractional decomposition have been studied as a function of laser fluence, irradiation frequency, reactant pressure, and added inert bath gas. Both absorption cross section and fractional decomposition are approximately in-dependent of pressure of 2,2-dimethyloxetane below 50 x W3 torr and increase with pressure at higher pressures of 2,2-dimethyloxetane. At pressures sufficiently low that collisions are negligible during the laser pulse, added inert gases reduce the amount of decomposition. Calculations of the fractional decomposition have been carried out based on RRKM theory and assuming eit,her a Boltzmann or a Poisson intermolecular energy distribution. Master equation calculations of both absorption and decomposition for 10R20 irradiation have also been performed. Agreement between observed and calculated results for 10R20 irradiation could be obtained only by assuming that most, but not all, of the molecules in the irradiated volume absorb the laser radiatinn. Differences between the absorptions of the 10R20 and 9P20 lines and in the resulting extents of decomposition indicate that the fraction of irradiated molecules which absorbs 9P20 radiation is smaller than the fraction which absorbs lQR20 radiation.