Theoretical investigation of the Cs exchange reaction between CsI molecule and Cs atom

Kobayashi, Takanori; Hashimoto, Masashi; Yokoyama, Keiichi  

To investigate the possibility of the Cs exchange reaction between CsI molecule and Cs atom, we have analyzed the Cs-I-Cs triatomic molecule by using quantum chemistry calculation. And, by using the newly developed capture model, the Cs exchange reaction rate and its temperature dependence were also estimated. The stabilization energy for CsICs formation is calculated as 12 kcal mol, which is much smaller than the calculated Cs-I bond energy of 82 kcal mol-1(spin-orbit correlation is not included). However, the bond lengths of both Cs-I are optimized as the same value (3.57 A). That is, Cs of CsI and colliding Cs atom cannot be distinguished if the triatomic structure is formed. And 2-dimensional potential energy surface around CsI against Cs atom shows that the reaction has no entrance barrier. The reaction rate was estimated to be the same value as the collision rate and little temperature dependence would be expected.