title: Two-photon voltmeter for measuring a molecular electric field.
abstract: We present a new approach for determining the strength of the dipolar solute-induced reaction field, along with the ground- and excited-state electrostatic dipole moments and polarizability of a solvated chromophore, using exclusively one-photon and two-photon absorption measurements. We verify the approach on two benchmark chromophores N,N-dimethyl-6-propionyl-2-naphthylamine (prodan) and coumarin 153 (C153) in a series of toluene/dimethyl sulfoxide (DMSO) mixtures and find that the experimental values show good quantitative agreement with literature and our quantum-chemical calculations. Our results indicate that the reaction field varies in a surprisingly broad range, 0-10(7)  V cm(-1) , and that at close proximity, on the order of the chromophore radius, the effective dielectric constant of the solute-solvent system displays a unique functional dependence on the bulk dielectric constant, offering new insight into the close-range molecular interaction.
authors.affiliation: Deptartment of Physics, Montana State University, 264 EPS, Bozeman, MT 59717 (USA). rebane@physics.montana.edu.|National Institute of Chemical Physics and Biophysics, Tallinn (Estonia). rebane@physics.montana.edu.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Rebane
authors.affiliation: Deptartment of Physics, Montana State University, 264 EPS, Bozeman, MT 59717 (USA).
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Wicks
authors.affiliation: Deptartment of Physics, Montana State University, 264 EPS, Bozeman, MT 59717 (USA).
authors.forename: Mikhail
authors.initials: M
authors.lastname: Drobizhev
authors.affiliation: Air Force Research Lab, Wright Patterson Air Force Base, Dayton, OH (USA).
authors.forename: Thomas
authors.initials: T
authors.lastname: Cooper
authors.affiliation: National Institute of Chemical Physics and Biophysics, Tallinn (Estonia).
authors.forename: Aleksander
authors.initials: A
authors.lastname: Trummal
authors.affiliation: National Institute of Chemical Physics and Biophysics, Tallinn (Estonia).|Tallinn Institute of Technology, Tallinn (Estonia).
authors.forename: Merle
authors.initials: M
authors.lastname: Uudsemaa
mesh_terms: D004574:Electromagnetic Fields; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D017785:Photons / Q000627:therapeutic use*
keywords: intramolecular charge transfer; molecular reaction field; solvatochromism; solvent effects; two-photon absorption spectroscopy