Abstract
The vibration frequencies found in the excited states of the molecules CO2, CS2, H2O, ClO2, SO2, O3, NH3, PCl3, C2H2, C2H4, C6H6 and (CH3)2CO are considered. The frequencies appearing most strongly in all cases, and in most cases the only frequencies occurring, are totally symmetrical. This is in accord with the extension of the Franck‐Condon principle to such molecules by Herzberg and Teller.