Excited state molecular configuration of biphenyl

Contributions of different electronic states to Raman scattering have been studied by critical analyses of Raman excitation profiles of several normal modes of vibration of biphenyl. In this context, the possible structure and other interesting properties of the molecule in the excited electronic states have been discussed. It is found that the first allowed transition to the excited state occurs at 248 nm whose major geometry change involves CC stretching vibrations, whereas, for the second allowed transition (corresponding to 205 nm) inter (i.e., substituent-sensitive) and intra (i.e., ring-breathing) ring CC stretching and in plane CCH angle bending modes are important.