Search

Absorption and emission spectra of 4-amino-4’-nitrodiphenyl sulfide in polar and nonpolar solvents were used to characterize and assign the low-energy excited states of the molecule. Fluorescence-excitation anisotropy spectra, fluorescence and phosphorescence lifetimes, and fluorescence quantum yields were also used to characterize the photophysics of these states. The lowest-energy, fluorescent singlet state was determined to be an intramolecular charge transfer (ICT) state involving transfer of a full electron charge from the amino to the nitro group yielding a dipole moment of ∼50 D. A low-energy, intense absorption band is assigned as a transition to a different ICT state involving a partial electron charge transfer from sulfur to the nitro group. [ABSTRACT FROM AUTHOR]

Two-color, photon-gated photochemical hole burning (PHB) is observed in the absorption spectrum of a photoadduct of anthracene and tetracene (A–T) in a polymer matrix at 1.5 K. A–T undergoes PHB when irradiated with narrow band exciting light into the 0–0 band of the S1 ← S0 absorption. The efficiency of this PHB process is enhanced by simultaneous irradiation near the maximum of the Tn ← T1 absorption of A–T. Holewidths of less than 0.07 cm-1 have been observed for this photochemical cleavage of A–T. PHB was not observed for the related photoadduct dianthracene (A2) under similar irradiation conditions. [ABSTRACT FROM AUTHOR]