title: Two-photon photosensitized production of singlet oxygen in water.
abstract: Singlet molecular oxygen (a(1)Delta(g)) has been produced and optically detected in time-resolved experiments upon nonlinear two-photon excitation of a photosensitizer dissolved in water. For a given sensitizer, specific functional groups that impart water solubility and that give rise to larger two-photon absorption cross sections are, in many cases, not conducive to the production of singlet oxygen in high yield. This issue involves the competing influence of intramolecular charge transfer that can be pronounced in aqueous systems; more charge transfer in the chromophore facilitates two-photon absorption but decreases the singlet oxygen yield. This phenomenon is examined in a series of porphyrins and vinyl benzenes.
authors.affiliation: Department of Chemistry, University of Aarhus, DK-8000 Arhus, Denmark.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Frederiksen
authors.forename: Sean P
authors.initials: SP
authors.lastname: McIlroy
authors.forename: Christian B
authors.initials: CB
authors.lastname: Nielsen
authors.forename: Lars
authors.initials: L
authors.lastname: Nikolajsen
authors.forename: Esben
authors.initials: E
authors.lastname: Skovsen
authors.forename: Mikkel
authors.initials: M
authors.lastname: Jørgensen
authors.forename: Kurt V
authors.initials: KV
authors.lastname: Mikkelsen
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ogilby