title: Charge transfer by electronic excitation: Direct measurement by high resolution spectroscopy in the gas phase.
abstract: We report a quantitative measurement of the amount of charge that is transferred when the single ammonia complex of the photoacid beta-naphthol (2HNA) is excited by light. The measurement was made by comparing the permanent electric dipole moments of cis-2HNA in its ground (S(0)) and excited (S(1)) states, determined by Stark-effect studies of its fully resolved S(1)<--S(0) electronic spectrum. While the increase in electron transfer from the donor (NH(3)) to the acceptor (2HN) upon excitation is small ( approximately 0.05e), it is sufficient to redshift the electronic spectrum of the complex by approximately 600 cm(-1) ( approximately 0.1 eV). Thereby explored is the incipient motion of the acid-base complex along the excited state (electron-coupled) proton transfer coordinate.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Fleisher
authors.forename: P J
authors.initials: PJ
authors.lastname: Morgan
authors.forename: D W
authors.initials: DW
authors.lastname: Pratt