On the electric dipole moments of asymmetric tops: measurement by high-resolution electronic spectroscopy in the gas phase.

Reported here are Stark-effect measurements of the permanent electric dipole moments of two structural isomers of aminobenzonitrile, 2ABN and 3ABN, using high-resolution laser molecular beam techniques. When combined with previous results on 4ABN, the data show that each structural isomer has a unique dipole moment, in both its ground (S(0)) and electronically excited (S(1)) states, thereby providing a means of distinguishing them. Possible applications of the method to other, biologically relevant molecules are discussed.