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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Photolysis of 4-Oxo-2-pentenal in the 190-460 nm Region
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Photolysis of 4-Oxo-2-pentenal in the 190-460 nm Region

机译：在190-460 nm区域内光解4-氧代-2-戊烯

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摘要

We have studied the gas-phase photolysis of 4-oxo-2-pentenal by laser photolysis combined with cavity ringdown spectroscopy. Absorption cross sections of cis- and trans-4-oxo-2-pentenal have been measured in the 190-460 nm region. The product channel following 193, 248, 308, and 351 nm photolysis of 4-oxo-2-pentenal was investigated. The HCO radical is a photodissociation product of 4-oxo-2-pentenal only at 193 and 248 nm. The HCO quantum yields from the photolysis of a mainly trans-4-oxo-2-pentenal sample are 0.13 +/- 0.02 and 0.014 +/- 0.003 at 193 and 248 nm, where errors quoted (1 sigma) represent experimental scatter. The HCO quantum yields from the photolysis of a mainly cis-4-oxo-2-pentenal sample are 0.078 +/- 0.012 and 0.018 +/- 0.007 at 193 and 248 nm, where errors quoted (1 sigma) represent experimental scatter. The endproducts from 193, 248, 308, and 351 nm photolysis of 4-oxo-2-pentenal (the 4-oxo-2-pentenal sample had a tran/cis ratio of 1.062:1) have been determined by FTIR. Ethane, methyl vinyl ketone, and 5-methyl-3Hfuran-2-one have been observed, suggesting the occurrence of 4-oxo-2-pentenal photolysis pathways such as CH3COCH=CHCHO + h nu -> CH3 + COCH=CHCHO, CH3COCH=CHCHO + h nu -> CH3COCH=CH2 + CO, and CH3COCH=CHCHO + h nu -> 5-methyl-3H-furan-2-one. The estimated yields for the CH3 + COCH = CHCHO channel are about 25%, 33%, 31 %, and 23% at 193, 248, 308, and 351 nm, respectively. The absolute uncertainties in the determination of CH3 + COCH=CHCHO yields are within 55% at 193 nm, and 65% at 248, 308, and 351 nm. The estimated yields for the CH3COCH=CH2 + CO channel are about 25%, 23%, 40%, and 33% at 193, 248, 308, and 351 nm, respectively. The absolute uncertainties in the determination of CH3COCH=CH2 yields are within 80% at 193 and 248 nm and 65% at 308 and 351 nm. The estimated yields for the 5-methyl-3H-furan-2-one channel are about 1.2%, 2.1%, 5.3%, and 5.5% at 193, 248, 308, and 351 nm, respectively. The absolute uncertainties in the determination of 5-methyl-3H-furan-2-one yields are about 23%, 86%, 40%, and 46% at 193, 248, 308, and 351 nm. Results from our investigation indicate that photolysis is a dominant removal pathway for 4-oxo-2-pentenal degradation in the atmosphere.
机译：我们已经研究了通过激光光解结合腔衰荡光谱技术对4-氧代-2-戊烯进行气相光解。已在190-460 nm范围内测量了顺式和反式4-氧代-2-戊烯的吸收截面。研究了193、248、308和351 nm对4-氧代-2-戊烯进行光解后的产物通道。 HCO自由基仅在193和248 nm处为4-氧代-2-戊烯的光解产物。在193和248 nm处，主要是反式4-氧-2-戊烯样品的光解HCO量子产率为0.13 +/- 0.02和0.014 +/- 0.003，其中引用的误差（1 sigma）表示实验散射。在193和248 nm处，主要是顺式4-氧代-2-戊烯样品的光解HCO量子产率为0.078 +/- 0.012和0.018 +/- 0.007，其中引用的误差（1 sigma）表示实验散射。通过FTIR测定了4-氧代-2-戊烯醛（4-氧代-2-戊烯醛样品的反式/顺式比为1.062：1）在193、248、308和351 nm处的光解终产物。观察到乙烷，甲基乙烯基酮和5-甲基-3H呋喃-2-酮，表明发生了4-氧代-2-戊烯光解途径，例如CH3COCH = CHCHO + h nu-> CH3 + COCH = CHCHO，CH3COCH ＝ CHCHO + h nu-> CH 3 COCH ＝ CH 2 + CO，并且CH 3 COCH ＝ CHCHO + h nu-> 5-甲基-3H-呋喃-2-酮。 CH3 + COCH = CHCHO通道的估计产量在193、248、308和351 nm处分别约为25％，33％，31％和23％。测定CH3 + COCH = CHCHO产率的绝对不确定性在193 nm处在55％以内，在248、308和351 nm处在65％以内。 CH3COCH = CH2 + CO通道的估计产率在193、248、308和351 nm分别约为25％，23％，40％和33％。测定CH3COCH = CH2产率的绝对不确定性在193和248 nm处在80％以内，在308和351 nm处在65％以内。 5-甲基-3H-呋喃-2-酮通道在193、248、308和351 nm处的估计产率分别约为1.2％，2.1％，5.3％和5.5％。在193、248、308和351 nm下测定5-甲基-3H-呋喃-2-酮收率的绝对不确定性约为23％，86％，40％和46％。我们调查的结果表明，光解是大气中4-氧-2-戊烯降解的主要去除途径。

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