Terrylene excitation spectra

Figure 2. Fluorescence excitation spectrum at 1.4 K of terrylene in a p-terphenyl single crystal in the spectral region of site Xi ( 580.4 nm). The narrow features are the excitation lines of single terrylene molecules. The laser was scanned in 32 seconds over the displayed frequency range at an intensity of 25mW/cm (fromRef.6).

The correlation method was applied to a thorough study of spectral diffusion of single terrylene molecules in polyethylene [44, 76], and later on to other systems [81]. Once a single molecule line was identified in the excitation spectrum, the laser was brought into resonance with the line, and the correlation function of the emitted fluorescence was recorded. For most single molecules studied (around 80%), no clear correlation appeared between 1 is and 100 s, i.e. the contrast of the correlation was weaker than experimental noise. This is in general agreement with bulk studies of... 

Fig. 9.9 (a) Light microscope image of an optical fiber to which a terrylene-doped p-terphenyl host crystal has been attached, (b) Excitation spectrum of the terryiene molecule at T = 1.4 K. Reprinted with permission from Michaeiis et al. (2000). Copyright 2000, Nature Pub-iishing Group. 

The steady state absorption and fluorescence spectra of both dendrimer generations 1 and 2 are depicted in Fig. 2. The former are merely superpositions of the absorption spectra of both chromophores involved. In the fluorescence, however, the peryleneimide part is almost completely quenched compared to the model compound. Instead, the fluorescence at wavelengths longer than 650 nm almost completely resembles the emission spectrum of the terrylene-diimide model compound 3. This feature is a strong indication that within these dendrimers the excitation energy is efficiently transferred from the peryleneimide to the terrylenediimide. 

Figure 10. Vibrationally resolved fluorescence spectra of terrylene in polyethylene (r= 1.4 K). Tlie bulk spectrum was obtained with excitation near the peak of the inhomogeneously broadened origin band. A-E represent spectra of different molecules which are described in the text. The average time to collect the single molecule spectra was several hundred seconds (from Ref. 38).

---