Resonance Raman Effect of Carbonyl Group as a Probe of Its π-Electron State

Abstract
By examining the occurrence or absence of a resonance Raman effect for a carbonyl bond-stretching vibration, one can achieve a unique characterization of the carbonyl π-electrons. It can be concluded, for example, that the carbonyl π-electrons of nicotinamide do not migrate into the ring π-electron orbitals responsible for the 265-nanometer band, whereas those of dihydronicotinamide do migrate into orbitals responsible for the 340-nanometer band.