Dissociation energy of the benzenewater van der Waals complex

The dissociation energy of the complex C6H6·H2O was determined by the threshold difference method. These complexes were produced in molecular beams via the expansion of a mixture of helium, and benzene and water vapours in the ratio of 96:3:1. The method requires the ionization potential of C6H6 and the appearance potential of C6H+6 from C6H6·H2O, the difference between which is the dissociation energy. The necessary values are 9.246 and 9.344 ± 0.012 eV, respectively, from which D(C6H6·H2O) = 0.098 ± 0.012 eV = 2.25 ± 2.25 ± 0.28 kcal mol−1. The ionization potential of C6H6·H2O is 9.170 ± 0.014 eV, which leads to the dissociation energy of the complex ion of D([C6H6·H2O]+) = 4.0 ± 0.4 kcal mol−1.