Pressure Effects on Single Molecules of Terrylene in p-Terphenyl

Abstract

Abstract Fluorescence excitation spectra of single molecules and persistent holes of terrylene in p-terphenyl crystals were investigated under hydrostatic pressure up to 10510 hPa. Single-molecule lines could be observed around all four inhomogeneous bands X1 to X4. They showed a linear and reversible pressure shift between -0.92 MHz/hPa and -1.55 MHz/hPa with no clear differences between the inhomogeneous bands. The relative fluctuations of the pressure shift parameter between different molecules are larger than for pentacene in p-terphenyl which indicates a less well-ordered local environment of the dopant molecules. Persistent hole-burning was possible in the bands X1 and X3 of the same samples in which single-molecule lines were observed. The pressure shift of the hole spectra (which are close to the band center) is smaller than the shift of the single-molecule lines (in the wings of the band). Hence, the molecules seem to feel different local compressibilities.