The photolysis of ethylene at 193 nm

Abstract

The photolysis of ethylene has been studied at pressures from 50 to 3000 Torr using a pulsed ArF excimer laser at 193.3 nm. Major products were acetylene, n-butane, 1-butene, ethane, and 1,3-butadiene, with smaller amounts of propane, propene, methane, and allene. Quantum yields varied with pressure and reaction time; the latter dependence is ascribed to secondary photolysis of butene and butadiene. The reaction products are accounted for by three primary processes:[Formula: see text]followed by reactions of H, [Formula: see text] and C2H5 radicals. The vibrationally excited C2H3radical can decompose to H + C2H2 or can be stabilized by collision. The pressure dependence of the quantum yields of the primary processes [1]–[3] is complex, and a photodissociation mechanism involving several intermediates and excited states of ethylene is presented to account for the present results and previous measurements at 185 nm. Keywords: ethylene, uv photolysis.

Photochemical processes on Titan: Irradiation of mixtures of gases that simulate Titan's atmosphere

“…The ethyl radicals can combine to give n-butane (10), react with hydrogen atoms to give ethane (11) or dissociate to give methyl radicals (12). The subsequent reactions of these radicals with ethylene give the wide array of products observed in the photolysis of ethylene and suggest that it is the precursor of the bulk of the hydrocarbons observed in the atmosphere of Titan (9)-(14) (Grioux et al, 1989),…”

Detection of HO<sub>2</sub> by laser-induced fluorescence: calibration and interferences from RO<sub>2</sub> radicals

“…Again, the concentration of organic compounds is chosen, so that all OH is consumed within the time between production of OH in the radical source and sampling by the instrument (OH reactivity approximately 300 s −1 ). Since hydrocarbons were added upstream of the photolysis region of the radical source, photolysis of these hydrocarbons at 185 nm may occur (Demers et al, 1978;Giroux et al, 1989). In order to test for effects of photolysis on experiments conducted here, the fluorescence signal was measured, when hydrocarbons were mixed in dry air, so that radicals are only produced by photolysis of the hydrocarbon.…”

Association Reaction of Gaseous C2H4 in Femtosecond Laser Filaments Studied by Time-of-Flight Mass Spectrometry

“…Photolysis of ethylene has been studied in the vacuum ultraviolet (VUV) region . Gas chromatography of the products obtained by the many-body reaction by VUV light irradiation revealed that four-carbon molecules containing a larger number of hydrogen atoms, C 4 H m ( m = 6, 8, and 10), are the dominant products, suggesting that the association reaction product yield is different from that in the present case.…”