title: 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.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Mitchell
authors.forename: P J
authors.initials: PJ
authors.lastname: Morgan
authors.forename: D W
authors.initials: DW
authors.lastname: Pratt