Push-pull molecules in the gas phase: stark-effect measurements of the permanent dipole moments of p-aminobenzoic acid in its ground and electronically excited states.
Stark effect measurements of the permanent electric dipole moments of p-aminobenzoic acid (PABA) in the gas phase are reported based on studies of its fully resolved S1<--S0 electronic spectrum in the presence of an electric field. Ground-state (S0) PABA has mu = 3.3 D, whereas excited-state (S1) PABA has mu = 4.4 D. Despite PABA's reputation as a "push-pull" molecule, the photon-induced change in both the magnitude and orientation of mu is relatively small. Possible reasons for this behavior are discussed.
Mitchell
D M
DM
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Morgan
P J
PJ
Pratt
D W
DW