P-Terphenyls

Kador L, Horne D E and Moerner W E 1990 Optioal deteotion and probing of single dopant moleoules of pentaoene in a p-terphenyl host by means of absorption speotrosoopy J. Phys. Chem. 94 1237-48... 

Orrit M and Bernard J 1990 Single pentaoene moleoules detested by fluoresoenoe exoitation in a p-terphenyl orystal Phys. Rev. Lett. 65 2716-19... 

Ambrose W P, Basche T and Moerner W E 1991 Detection and spectroscopy of single pentacene molecules in a p-terphenyl crystal by means of fluorescence excitation J. Phys. Chem 95 7150-63... 

Kummer S, Basche T and Brauchle C 1994 Terrylene in p-terphenyl a novel single crystalline system for single molecule spectroscopy at low temperatures Chem. Phys. Lett. 229 309-16... 

Reilly P D and Skinner J L 1995 Spectral diffusion of individual pentacene molecules in p-terphenyl crystal theoretical model and analysis of experimental data J. Phys. Chem 102 1540-52... 

Wild U P, Guttler F, Pirotta M and Renn A 1992 Single molecule spectroscopy stark effect of pentacene in p-terphenyl Chem. Phys. Lett. 193 451-5... 

Guttler F, Croci M, Renn A and Wild U P 1996 Single molecule polarization spectroscopy pentacene in p-terphenyl Chem. Phys. 211 421-30... 

Tchenio P, Myers A B and Moerner W E 1993 Dispersed fluorescence spectra of single molecules of pentacene in p-terphenyl J. Chem. Phys. 97 2491-3... 

Fleury L, Tamarat P, Lounis B, Bernard J and Orrit M 1995 Fluorescence spectra of single pentacene molecules in p-terphenyl at 1.7 K Chem. Phys. Lett. 236 87-95... 

Kulzer F, Kummer S, Matzke R, Brauchle C and Basche T 1997 Single-molecule optical switching of terrylene in p-terphenyl Nature 387 688-91... 

Kulzer F, Koberling F, Christ T, Mews A and Basche T 1999 Terrylene in p-terphenyl single-molecule experiments at... 

Fig. 12. Chemical structure of the mesogenic 4-cyano-4 -n-pentyl-p-terphenyl (T15)...

Structure of 4-cyano-4 -n-pentyl-p-terphenyl (T15) is shown in Fig. 12. This compound, first prepared by Gray et al. [82], exhibits a nematic phase with a wide temperature range. 

Forster (1968) points out that R0 is independent of donor radiative lifetime it only depends on the quantum efficiency of its emission. Thus, transfer from the donor triplet state is not forbidden. The slow rate of transfer is partially offset by its long lifetime. The importance of Eq. (4.4) is that it allows calculation in terms of experimentally measured quantities. For a large class of donor-acceptor pairs in inert solvents, Forster reports Rg values in the range 50-100 A. On the other hand, for scintillators such as PPO (diphenyl-2,5-oxazole), pT (p-terphenyl), and DPH (diphenyl hexatriene) in the solvents benzene, toluene, and p-xylene, Voltz et al. (1966) have reported Rg values in the range 15-20 A. Whatever the value of R0 is, it is clear that a moderate red shift of the acceptor spectrum with respect to that of the donor is favorable for resonant energy transfer. 

According to Ludwig (1968), there is a some similarity between UV- and high-energy-induced luminescence in liquids. In many cases (e.g., p-ter-phenyl in benzene), the luminescence decay times are similar and the quenching kinetics is also about the same. However, when a mM solution of p-terphenyl in cyclohexane was irradiated with a 1-ns pulse of 30-KeV X-rays, a long tail in the luminescence decay curve was obtained this tail is absent in the UV case. This has been explained in terms of excited states produced by ion neutralization, which make a certain contribution in the radiolysis case but not in the UV case (cf. Sect. 4.3). Note that the decay times obtained from the initial part of the decay are the same in the UV- and radiation-induced cases. Table 4.3 presents a brief list of luminescence lifetimes and quantum yields. 

With the advent of picosecond-pulse radiolysis and laser technologies, it has been possible to study geminate-ion recombination (Jonah et al, 1979 Sauer and Jonah, 1980 Tagawa et al 1982a, b) and subsequently electron-ion recombination (Katsumura et al, 1982 Tagawa et al, 1983 Jonah, 1983) in hydrocarbon liquids. Using cyclohexane solutions of 9,10-diphenylanthracene (DPA) and p-terphenyl (PT), Jonah et al. (1979) observed light emission from the first excited state of the solutes, interpreted in terms of solute cation-anion recombination. In the early work of Sauer and Jonah (1980), the kinetics of solute excited state formation was studied in cyclohexane solutions of DPA and PT, and some inconsistency with respect to the solution of the diffusion equation was noted.1... 

Figure 5.12 Polyaromatic hydrocarbon species (1) phenanthrene, (2) anthracene, (3) pyrene, (4) benz[o]anthracene, (5) chrysene, (6) naphthacene, (7) benzo[c]phenanthrene, (8) benzo[ghi] fluoranthene, (9) dibenzo[c,g]phenanthrene, (10) benzo[g/ ]perylene, (11) triphenylene, (12) o-terphenyl, (13) m-terphenyl, (14) p-terphenyl, (15) benzo[o]pyrene, (16) tetrabenzonaphthalene, (17) phenanthro[3,4-c]phenanthrene, (18) coronene...

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