Resonance Raman Spectra of the Transient Cl2 and Br2 Radical Anions

The resonance Raman spectra of the short-lived radical anions ClImage 2− and BrImage − in aqueous solution are reported. The observed wavenumbers of 279 cm−1 for ClImage − and 177 cm−1 for BrImage − are about 10% higher than those published for the corresponding species isolated in solid argon matrices.

Under the assumption of a Morse potential. harmonic frequencies and anharmonicity constants are calculated to be 286.4 and 3.83 cm−1 for ClImage − and 187.2 and 5.17 cm−1 for BrImage −. These values lead to extrapolated dissociation energies of 0.66 and 0.21 eV, respectively. These results are compared with those from matrix-isolation studies at low temperatures and work in the gas phase.