Akhgarnusch Amou, Tang Wai Kit, Zhang Han, Siu Chi-Kit, Beyer Martin K
Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
Phys Chem Chem Phys. 2016 Sep 14;18(34):23528-37. doi: 10.1039/c6cp03324e. Epub 2016 Aug 8.
The recombination reactions of gas-phase hydrated electrons (H2O)n˙(-) with CO2 and O2, as well as the charge exchange reaction of CO2˙(-)(H2O)n with O2, were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry in the temperature range T = 80-300 K. Comparison of the rate constants with collision models shows that CO2 reacts with 50% collision efficiency, while O2 reacts considerably slower. Nanocalorimetry yields internally consistent results for the three reactions. Converted to room temperature condensed phase, this yields hydration enthalpies of CO2˙(-) and O2˙(-), ΔHhyd(CO2˙(-)) = -334 ± 44 kJ mol(-1) and ΔHhyd(O2˙(-)) = -404 ± 28 kJ mol(-1). Quantum chemical calculations show that the charge exchange reaction proceeds via a CO4˙(-) intermediate, which is consistent with a fully ergodic reaction and also with the small efficiency. Ab initio molecular dynamics simulations corroborate this picture and indicate that the CO4˙(-) intermediate has a lifetime significantly above the ps regime.
在T = 80 - 300 K的温度范围内，利用傅里叶变换离子回旋共振（FT - ICR）质谱研究了气相水合电子(H2O)n˙(-)与CO2和O2的复合反应，以及CO2˙(-)(H2O)n与O2的电荷交换反应。将速率常数与碰撞模型进行比较表明，CO2以50%的碰撞效率发生反应，而O2的反应则慢得多。纳米量热法对这三个反应给出了内部一致的结果。转换到室温凝聚相，得到CO2˙(-)和O2˙(-)的水合焓，ΔHhyd(CO2˙(-)) = -334 ± 44 kJ mol(-1)和ΔHhyd(O2˙(-)) = -404 ± 28 kJ mol(-1)。量子化学计算表明，电荷交换反应通过CO4˙(-)中间体进行，这与完全遍历反应以及低效率是一致的。从头算分子动力学模拟证实了这一情况，并表明CO4˙(-)中间体的寿命显著高于皮秒范围。
