Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
Phys Chem Chem Phys. 2011 Nov 7;13(41):18418-27. doi: 10.1039/c1cp21581g. Epub 2011 Aug 30.
A variety of combinations of oppositely charged ions have been reacted to examine the role of the charge state from a multiply protonated or multiply deprotonated reagent ion on the efficiency of conversion of a singly charged ion of opposite polarity to a singly charged ion of the same polarity as the reagent. Maximum efficiencies on the order of tens of percent were observed. A threshold for charge inversion was noted in all cases and, with one exception, a clear decrease in efficiency was also noted at high charge states. A model was developed to predict charge inversion efficiency based on charge states, cross-sections of the reactants, and relevant thermodynamic ion affinity values for the reactants and products. The model predicts a threshold for charge inversion, although the prediction does not match the observed threshold quantitatively. This discrepancy is likely due to a simplifying assumption that is not justified on a quantitative basis but which does reproduce the qualitative trend. The model does not predict the major decrease in efficiency at high charge states. However, calculations show that the kinetic energies of the charge inversion products can lead to significant scattering losses at high charge states of the ion-ion collision complex.
已经对各种带相反电荷的离子组合进行了反应，以研究多质子化或多去质子化试剂离子的荷质比对将单价相反极性离子转化为与试剂相同极性的单价离子的效率的作用。观察到了最大效率约为百分之几十的情况。在所有情况下都注意到了电荷反转的阈值，并且除了一个例外，在高电荷态下也注意到了效率明显下降。已经开发了一种基于电荷态、反应物的横截面以及反应物和产物的相关热力学离子亲合能值来预测电荷反转效率的模型。该模型预测了电荷反转的阈值，尽管该预测在数量上与观察到的阈值并不匹配。这种差异可能是由于简化假设所致，该假设在定量基础上没有得到证明，但确实再现了定性趋势。该模型无法预测在高电荷态下效率的大幅下降。然而，计算表明，在离子-离子碰撞复合物的高电荷态下，电荷反转产物的动能可能导致显著的散射损失。
