The kinetics of the C3H3 + C3H 3 reaction was investigated by using dipropargyl oxalate (DPO) as a new, halogen-free photolytic source for propargyl radicals in the gas phase. After laser-flash photolysis of DPO at 193 nm, the initial absorbance was determined at different wavelengths, and the results were compared with values obtained in analogous experiments using propargyl halides as precursors. A satisfactory agreement of the absorbances was found between 295 and 355 nm but differences were observed near 242 nm. The latter wavelength has also been proposed for C3H3 detection. Our results, however, indicate that this absorption is probably due to halogen-containing species. The rate coefficient of the C3H3 + C3H 3 reaction was then determined from time-resolved absorption measurements at 332.5 nm with DPO as precursor. Values of (2.7 ± 0.6) × 10-11 cm3 molecule-1 s-1 at 373 K, (2.8 ± 0.6) × 10-11 cm3 molecule -1 s-1 at 425 K, (3.5 ± 0.8) × 10 -11 cm3 molecule-1 s-1 at 500 K, and (4.1 ± 0.8) × 10-11 cm3 molecule -1 s-1 at 520 K were obtained with no significant pressure dependence between 1 and ca. 100 bar (140 bar for T = 373 K).
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry