Should bromoform absorb at wavelengths longer than 300 nm?

Peterson, Kirk A.; Francisco, Joseph S.
October 2002
Journal of Chemical Physics;10/1/2002, Vol. 117 Issue 13, p6103
Academic Journal
A theoretical study of the low-lying singlet and triplet electronic states of CHBr[sub 3] is presented. Calculations of excitation energies and oscillator strengths are presented using excited state coupled cluster response methods, as well as the complete active space self-consistent field method with the full Breit-Pauli spin-orbit operator. These calculations predict that for CHBr[sub 3] there is only one singlet state, the ùA[sub 2], that is accessible by wavelengths longer than 234 nm. It is, however, predicted to be very weakly absorbing, but may strongly overlap at shorter wavelengths with a higher &Btilde;¹E state, which itself is predicted to be strongly absorbing. There is one triplet state, the ã³A[sub 2], that lies well below the ùA[sub 2] state and has a predicted absorption maximum at about 270 nm. The band origin of the ã³A[sub 2] is predicted to lie around 297 nm, but this C[sub 3υ] symmetry minimum is calculated to be a second-order transition state, ultimately leading to dissociation to HCBr[sub 2] + Br.


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