title: Ultrafast Elementary Photochemical Processes of Organic Molecules in Liquid Solution.
abstract: Ultrafast photochemical reactions in liquids occur on similar or shorter time scales compared to the equilibration of the optically populated excited state. This equilibration involves the relaxation of intramolecular and/or solvent modes. As a consequence, the reaction dynamics are no longer exponential, cannot be quantified by rate constants, and may depend on the excitation wavelength contrary to slower photochemical processes occurring from equilibrated excited states. Such ultrafast photoinduced reactions do no longer obey the Kasha-Vavilov rule. Nonequilibrium effects are also observed in diffusion-controlled intermolecular processes directly after photoexcitation, and their proper description gives access to the intrinsic reaction dynamics that are normally hidden by diffusion. Here we discuss these topics in relation to ultrafast organic photochemical reactions in homogeneous liquids. Discussed reactions include intra- and intermolecular electron- and proton-transfer processes, as well as photochromic reactions occurring with and without bond breaking or bond formation, namely ring-opening reactions and cis-trans isomerizations, respectively.
authors.affiliation: Department of Physical Chemistry, Sciences II, University of Geneva , 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Tatu
authors.initials: T
authors.lastname: Kumpulainen
authors.affiliation: Department of Physical Chemistry, Sciences II, University of Geneva , 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lang
authors.affiliation: Department of Physical Chemistry, Sciences II, University of Geneva , 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Arnulf
authors.initials: A
authors.lastname: Rosspeintner
authors.affiliation: Department of Physical Chemistry, Sciences II, University of Geneva , 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Eric
authors.identifier: http://orcid.org/0000-0002-9580-9683
authors.initials: E
authors.lastname: Vauthey