| Abstract
| - The dissociative photoionization studies have been performed for a set of dihalomethane CH2XY (X,Y = Cl,Br, and I) molecules employing the threshold photoelectron photoion coincidence (TPEPICO) technique.Accurate dissociation onsets for the first and second dissociation limits have been recorded in the 10−13 eVenergy range, and ionization potentials have been measured for these compounds. By using our experimentaldissociation onsets and the known heat of formation of CH2Cl2 molecule, it has been possible to derive the0 and 298 K heats of formation of all six neutral dihalomethanes as well as their ionic fragments, CH2Cl+,CH2Br+, and CH2I+, to a precision better than 3 kJ/mol. These new measurements serve to fill the lack ofreliable experimental thermochemical information on these molecules, correct the old literature values by upto 19 kJ/mol, and reduce their uncertainties. From our thermochemical results it has also been possible toderive a consistent set of bond dissociation energies for the dihalomethanes.
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