Ziółkowski Marcin, Schatz George C, Viggiano A A, Midey Anthony, Dotan Itzhak
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
Air Force Research Laboratory, Space Vehicles Directorate, 3500 Aberdeen Ave, Kirtland AFB, New Mexico 87117, USA.
J Chem Phys. 2014 Jun 7;140(21):214307. doi: 10.1063/1.4879805.
We present theory and experiments which describe charge transfer from the X³Σg⁻ and a(1)Δg states of molecular oxygen and atomic and molecular cations. Included in this work are new experimental results for O2(a(1)Δg) and the cations O(+), CO(+), Ar(+), and N₂⁺, and new theory based on complete active space self-consistent field method calculations and an extended Langevin model to calculate rate constants for ground and excited O2 reacting with the atomic ions Ar(+), Kr(+), Xe(+), Cl(+), and Br(+). The T-shaped orientation of the (X - O2)(+) potential surface is used for the calculations, including all the low lying states up to the second singlet state of the oxygen molecule b¹Σ(g)⁺. The calculated rate constants for both O₂(X³Σg⁻) and O2(a(1)Δg) show consistent trends with the experimental results, with a significant dependence of rate constant on charge transfer exothermicity that does not depend strongly on the nature of the cation. The comparisons with theory show that partners with exothermicities of about 1 eV have stronger interactions with O2, leading to larger Langevin radii, and also that more of the electronic states are attractive rather than repulsive, leading to larger rate constants. Rate constants for charge transfer involving O2(a(1)Δg) are similar to those for O₂(X³Σg⁻) for a given exothermicity ignoring the electronic excitation of the O2(a(1)Δg) state. This means (and the electronic structure calculations support) that the ground and excited states of O2 have about the same attractive interactions with ions.
我们展示了描述分子氧的X³Σg⁻和a(1)Δg态以及原子和分子阳离子之间电荷转移的理论和实验。这项工作包括O2(a(1)Δg)以及阳离子O(+)、CO(+)、Ar(+)和N₂⁺的新实验结果，以及基于完全活性空间自洽场方法计算和扩展朗之万模型的新理论，用于计算基态和激发态O2与原子离子Ar(+)、Kr(+)、Xe(+)、Cl(+)和Br(+)反应的速率常数。(X - O2)(+)势能面的T形取向用于计算，包括直至氧分子b¹Σ(g)⁺的第二单重态的所有低能态。O₂(X³Σg⁻)和O2(a(1)Δg)的计算速率常数与实验结果显示出一致的趋势，速率常数对电荷转移放热有显著依赖性，且这种依赖性并不强烈取决于阳离子的性质。与理论的比较表明，放热约为1 eV的反应伙伴与O2的相互作用更强，导致更大的朗之万半径，而且更多的电子态是吸引性的而非排斥性的，从而导致更大的速率常数。对于给定的放热情况，忽略O2(a(1)Δg)态的电子激发时，涉及O2(a(1)Δg)的电荷转移速率常数与O₂(X³Σg⁻)的相似。这意味着（并且电子结构计算也支持）O2的基态和激发态与离子具有大致相同的吸引相互作用。
