Wiens Justin P, Miller Thomas M, Shuman Nicholas S, Viggiano Albert A
Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
J Chem Phys. 2016 Dec 28;145(24):244312. doi: 10.1063/1.4972063.
Dissociative recombination of electrons with HCl, HCl, DCl, and DCl has been measured under thermal conditions at 300, 400, and 500 K using a flowing afterglow-Langmuir probe apparatus. Measurements for HCl and DCl employed the variable electron and neutral density attachment mass spectrometry (VENDAMS) method, while those for HCl and DCl employed both VENDAMS and the more traditional technique of monitoring electron density as a function of reaction time. At 300 K, HCl and HCl recombine with k = 7.7± × 10 cm s and 2.6 ± 0.8 × 10 cm s, respectively, whereas DCl is roughly half as fast as HCl with k = 1.1 ± 0.3 × 10 cm s (2σ confidence intervals). DCl recombines with a rate coefficient below the approximate detection limit of the method (≲5 × 10 cm s) at all temperatures. Relatively slow dissociative recombination rates have been speculated to be responsible for the large HCl and HCl abundances in interstellar clouds compared to current astrochemical models, but our results imply that the discrepancy must originate elsewhere.
利用流动余辉-朗缪尔探针装置，在300 K、400 K和500 K的热条件下，测量了电子与HCl、HCl、DCl和DCl的离解复合。HCl和DCl的测量采用可变电子和中性密度附着质谱法（VENDAMS），而HCl和DCl的测量则同时采用了VENDAMS和监测电子密度随反应时间变化的更传统技术。在300 K时，HCl和HCl的复合速率常数分别为k = 7.7±×10 cm³ s⁻¹和2.6±0.8×10 cm³ s⁻¹，而DCl的复合速率约为HCl的一半，k = 1.1±0.3×10 cm³ s⁻¹（2σ置信区间）。在所有温度下，DCl的复合速率系数均低于该方法的近似检测限（≲5×10 cm³ s⁻¹）。与当前的天体化学模型相比，星际云中HCl和HCl的丰度较高，有人推测这是由于离解复合速率相对较慢所致，但我们的结果表明，这种差异一定源于其他地方。
