Single-Molecule Spectroscopy and Persistent Hole Burning of Terrylene in p-Terphenyl: External-Field Effects

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Abstract
Fluorescence excitation spectra of single terrylene molecules in p-terphenyl crystals were investigated at low temperatures. The line shifts due to hydrostatic pressure and external electric fields were measured, with the electric field strength oriented either parallel or perpendicular to the k vector of the laser light. A linear Stark effect was found for most molecules, indicating local environments of low symmetry. In sites X1 and X3 (and XY, a photoproduct state), spectral hole burning was observed. Whereas the holes are stable in sites X1 and XY, they decay with a time constant of some minutes in X3. Pressure experiments were performed on the stable hole spectra in sites X1 and XY. In weakly doped samples, holes composed of very few molecular lines were generated with halfwidths distinctly narrower than twice the homogeneous linewidth.