Correlations between angular momenta of coincident product pairs

The correlation between angular momenta of the coincident product pairs formed in an elementary dissociation process has been investigated. Doppler shift measurements are used in connection with state-specific detection of scattered photofragments by laser-induced fluorescence. The method is demonstrated in the photodissociation of H2O2 and D2O2 at 193 and 266 nm where Doppler profiles of OH (OD) absorption lines are used to determine the (average) rotational energy of the OH (OD) partner molecule coincidently formed in the same elementary fragmentation process. At high product rotations the partner molecules are generated with comparable angular momenta, while at low rotational excitation a more complex correlation is observed. In addition to the partner fragment distribution, dissociation energies were determined to be 197 kJ/mol for HO–OH and 204 kJ/mol for DO–OD, which are significantly lower than the previously recommended values.