Rate constants and product ion distributions have been determined for thermal energy reactions of CO2+ with n-C4H10 and i-C4H10 by using an ion-beam apparatus. The total rate constants are (9.8 ± 2.0) × 10−10 and (1.0 ± 0.2) × 10−9 cm3 s−1 for n-C4H10 and i-C4H10, respectively. These values amount to about 75% of the collision rate constants estimated from the Langevin theory. C4H9+, C3Hn+ (n = 5—7), and C2Hn+ (n = 3—5) are produced from n-C4H10 with branching ratios of 6, 56, and 38%, while C4H9+ and C3Hn+ (n = 5—7) are formed from i-C4H10 with branching ratios of 7 and 93%, respectively. The lack of C2Hn+ fragments from i-C4H10 is attributed to a low probability of significant rearrangement of chemical bonds for the formation of the C2Hn+ fragments. The product ion distribution in the CO2+/n-C4H10 reaction is in good agreement with that predicted from the fragmentation pattern of n-C4H10+ at 13.78 eV, indicating that the CO2+/n-C4H10 reaction proceeds through a near-resonant charge transfer without momentum transfer.
通过使用离子束装置,已测定
CO2+与n-
C4H10和i- 的热能反应的速率常数和产物离子分布。n- 和i- 的总速率常数分别为(9.8 ± 2.0) × 10−10和(1.0 ± 0.2) × 10−9 cm³ s−1。这些数值约占根据拉让文理论估计的碰撞速率常数的75%。n- 产生的离子包括
C4H9+、C3Hn+(n = 5—7)和C2Hn+(n = 3—5),其分支比为6%、56%和38%;而从i- 形成的离子为 +和C3Hn+(n = 5—7),分支比分别为7%和93%。i- 中缺乏C2Hn+片段归因于在形成C2Hn+片段时
化学键发生显著重排的概率较低。 +/n- 反应中的产物离子分布与在13.78 eV下n- +的碎片化模式预测的结果非常一致,表明 +/n- 反应通过近共振电荷转移而不发生动量转移。