Parnis J Mark, King Kaitlynn A, Thompson Matthew G K
Department of Chemistry, Trent University, Peterborough, ON K9J 7B8, Canada.
J Mass Spectrom. 2009 May;44(5):652-61. doi: 10.1002/jms.1540.
The chemistry of ionized acetone:Ar mixtures under varying total gas flow rate and acetone:Ar mole ratio conditions has been studied using matrix-isolation techniques. Gaseous acetone diluted in excess argon gas was subjected to electron bombardment with 300-eV electrons. The products of subsequent reaction processes were matrix isolated and analyzed by Fourier transform infrared (FTIR) absorption spectroscopy. Products included 1-propen-2-ol (the enol isomer of acetone), methane, ketene, carbon monoxide, ethane, ethene, acetylene and tricarbon monoxide. Variations in the total flow rate of gas resulted in changes in the efficiency of product formation without significant changes in the relative amounts of the major species formed. Variations in the acetone:Ar mole ratio at fixed total gas flow resulted in striking variations in the products formed, demonstrating a shift from single acetone molecule-derived charge-transfer ionization chemistry at low acetone mole ratios, to processes consistent with the participation of two or more acetone molecules at intermediate mole ratios. These results are interpreted in the context of ion-molecule reaction processes, the onset of which occurs at intermediate acetone mole ratios. Ethane dehydrogenation products are proposed to result from product secondary ionization, a process that is prevalent at high ionizing electron fluxes.
采用基质隔离技术研究了在不同总气体流速和丙酮与氩气摩尔比条件下，离子化丙酮与氩气混合物的化学性质。将稀释于过量氩气中的气态丙酮用300电子伏特的电子进行电子轰击。后续反应过程的产物经基质隔离后，通过傅里叶变换红外（FTIR）吸收光谱进行分析。产物包括1-丙烯-2-醇（丙酮的烯醇异构体）、甲烷、乙烯酮、一氧化碳、乙烷、乙烯、乙炔和三氧化碳。气体总流速的变化导致产物生成效率的改变，而所形成的主要物种的相对量没有显著变化。在固定总气体流速下，丙酮与氩气摩尔比的变化导致所形成产物的显著变化，表明在低丙酮摩尔比时，从单丙酮分子衍生的电荷转移电离化学转变为在中等摩尔比时与两个或更多丙酮分子参与一致的过程。这些结果是在离子-分子反应过程的背景下进行解释的，其起始发生在中等丙酮摩尔比时。乙烷脱氢产物被认为是由产物二次电离产生的，这一过程在高电离电子通量下普遍存在。
