PRESSURE EFFECTS ON SINGLE MOLECULES OF TERRYLENE IN P-TERPHENYL

Fluorescence excitation spectra of single molecules and persistent hol es of terrylene in p-terphenyl crystals were investigated under hydros tatic pressure up to 10510 hPa. Single-molecule lines could be observe d around all four inhomogeneous bands X(1) to X(4). They showed a line ar and reversible pressure shift between -0.92 MHz/hPa and -1.55 MHz/h Pa with no clear differences between the inhomogeneous bands. The rela tive fluctuations of the pressure shift parameter between different mo lecules are larger than for pentacene in p-terphenyl which indicates a less well-ordered local environment of the dopant molecules. Persiste nt hole-burning was possible in the bands X(1) and X(3) of the same sa mples in which single-molecule lines were observed. The pressure shift of the hole spectra (which are close to the band center) is smaller t han the shift of the single-molecule lines (in the wings of the band). lit Hence, the molecules seem to feel different local compressibiliti es.