Department of Physical Sciences, Division of Atmospheric Sciences, University of Helsinki, P.O. Box 64, Helsinki FIN-00014, Finland.
J Chem Phys. 2010 Jan 14;132(2):024304. doi: 10.1063/1.3291213.
We discuss the possible role of energy nonaccommodation (monomer-cluster collisions that do not result in stable product formation due to liberated excess energy) in atmospheric nucleation processes involving sulfuric acid. Qualitative estimates of the role of nonaccommodation are computed using quantum Rice-Ramsberger-Kassel theory together with quantum chemically calculated vibrational frequencies and anharmonic coupling constants for small sulfuric acid-containing clusters. We find that energy nonaccommodation effects may, at most, decrease the net formation rate of sulfuric acid dimers by up to a factor of 10 with respect to the hard-sphere collision rate. A decrease in energy nonaccommodation due to an increasing number of internal degrees of freedom may kinetically slightly favor the participation of amines rather than ammonia as stabilizing agents in sulfuric acid nucleation, though the kinetic enhancement factor is likely to be less than three. However, hydration of the clusters (which always occurs in ambient conditions) is likely to increase the energy accommodation factor, reducing the role that energy nonaccommodation plays in atmospheric nucleation.
我们讨论了能量不适应（由于释放的过剩能量，单体-簇碰撞不会导致稳定产物形成）在涉及硫酸的大气成核过程中的可能作用。使用量子 Rice-Ramsberger-Kassel 理论以及通过量子化学计算得出的含小硫酸簇的振动频率和非谐耦合常数，对非适应作用的定性估计进行了计算。我们发现，能量不适应效应最多可能使硫酸二聚体的净形成速率相对于硬球碰撞速率降低 10 倍。由于内部自由度的增加而导致的能量不适应的减少可能在动力学上稍微有利于胺而不是氨作为硫酸成核的稳定剂，尽管动力学增强因子可能小于 3。然而，簇的水合（在环境条件下总是发生）可能会增加能量适应因子，从而降低能量不适应在大气成核中所起的作用。
