title: Two-photon photosensitized production of singlet oxygen.
abstract: Singlet molecular oxygen (a(1)Delta(g)) has been produced and optically detected upon two-photon nonlinear excitation of a sensitizer with a focused laser beam. The experiments were performed using toluene solutions with either a substituted difuranonaphthalene or a substituted distyryl benzene as the sensitizer. The data indicate that the two-photon absorption cross sections of the difuranonaphthalenes are comparatively large and depend significantly on the functional groups attached to the chromophore. The time-resolved 1270 nm phosphorescence signals used to characterize the production of singlet oxygen are limited in much the same way as signals from other two-photon spectroscopic studies (e.g., weak signals that can be masked by scattered radiation). Nevertheless, the two-photon singlet oxygen signals also reflect the unique advantages of this nonlinear optical technique (e.g., depth penetration in the sample afforded by irradiation in a spectral region void of the more dominant one-photon linear transitions and spatial resolution afforded by irradiation with a focused laser beam).
authors.affiliation: Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: P K
authors.initials: PK
authors.lastname: Frederiksen
authors.forename: M
authors.initials: M
authors.lastname: Jørgensen
authors.forename: P R
authors.initials: PR
authors.lastname: Ogilby