Determination of D00 (Ca…HBr) from full and half collision studies. Van der Waals and charge transfer contributions to the formation of Ca…HX (X = Cl, Br) complexes

The dissociation energy of the weakly bound complex Ca…HBr in it ground state D00 (Ca…HBr), has been determined using energy balance arguments. Byu combining collisional information from molecular beam studies on the Ca(3P) + HBr → CaBr(A)2II) + h reaction and spectroscopic infomration from the emission of the product ogf the reaction Ca + HBr → Ca…HBr →hv CaBr (A2II) + H, we find D00 (Ca…HBr) ≤ 270 ± 50 meV. The measured bond enery is duiscussed as due to the combined effect of interactions of van der Waals and ionic type. An empirical description of both these contributions accounts for the results obtained for Ca…HBr, as well as for those previously reported for Ca…HCl.