McLain Jason L, Poterya Viktoriya, Molek Christopher D, Jackson Douglas M, Babcock Lucia M, Adams Nigel G
Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
J Phys Chem A. 2005 Jun 16;109(23):5119-23. doi: 10.1021/jp0444159.
A technique has been developed to simultaneously determine recombination rate coefficients, alpha e, and initial concentrations of ion types that coexist in a flowing afterglow plasma. This was tested using the H3(+) + allene reaction in which two different C3H3+ isomers are produced. Use of an electrostatic Langmuir probe enabled the C3H3+ isomer branching ratios for propargyl and cyclic C3H3+ from this allene reaction and their alpha e to be determined over the temperature range 172-489 K. The study showed that the cyclic C3H3+ to propargyl C3H3+ branching ratios from the allene reaction varied from 50/50 at 172 K to 18/82 at 489 K. Over this temperature range, the alpha e for both isomers change only slightly. The room temperature alpha e values for propargyl and cyclic C3H3+ are (1.15 +/- 0.2) x 10(-7) and (8.00 +/- 0.1) x 10(-7) cm3/s, respectively. The data are discussed relative to current theories and in relation to fuel-rich flame chemistry, interstellar molecular synthesis, and modeling of Titan's atmosphere.
已开发出一种技术，可同时测定存在于流动余辉等离子体中的复合速率系数αe以及共存离子类型的初始浓度。使用H3(+) + 丙二烯反应对此进行了测试，该反应会生成两种不同的C3H3+异构体。使用静电朗缪尔探针能够确定此丙二烯反应生成的炔丙基和环状C3H3+的C3H3+异构体分支比及其在172 - 489 K温度范围内的αe。研究表明，丙二烯反应生成的环状C3H3+与炔丙基C3H3+的分支比从172 K时的50/50变化到489 K时的18/82。在此温度范围内，两种异构体的αe仅略有变化。炔丙基和环状C3H3+在室温下的αe值分别为(1.15 ± 0.2)×10(-7)和(8.00 ± 0.1)×10(-7) cm3/s。相对于当前理论以及与富燃料火焰化学、星际分子合成和土卫六大气模型相关的数据进行了讨论。
