Luminescent Films

The fluorescence lifetime was determined to be 1124ps for 35a, 785 ps for 35b, and 831 ps for 43 in dichloromethane, whereas in the corresponding amorphous films a nonexponential decay with shorter time constants was observed [118, 119]. These lifetimes are similar to the parent oligophenyls but different from fluorene (10 ns) [120, 121]. When applying oligophenyls as luminescent films, however, we must consider that photooxidation may occur if molecular oxygen is present [122, 123], The proposed pathway for the decomposition is... 

Crayston and coworkers have shown that vinylpyridine complex 10 may be electropolymerized efficiently in DMSO to yield an orange, luminescent film [33,34]. The method is much more controllable than that used in the traditional electropolymerization method for vinylbipyridine [35] and vinylterpyridine complexes [36]. 

When applying oligophenyls as luminescent films, however, it has to be taken into consideration that photooxidation may occur if molecular oxy-... 

Measures R, Houston W, Stephenson D (1974) LasCT induced fluraescent decay spectra — a new form of environmental signature. Opt Eng 13 494—501 Moroshkin V, Evdokimenko E, Gaft M et al (1997) Method of artificial luminescent films — a new method of luminescence analysis of minerals and rocks. Rocks Metals 3 63—72 NIST Atomic Spectra Database http //physics.nist.gov/PhysRefData/ASD/lines form.html Ollier N, Fuchs Y, Cavani O et al (2015) Influence of impurities on Cr " " luminescence properties in Brazilian emeralds and alexandrite minerals. Eur Mineral J (Pre published online)... 

Nanoporous materials have been produced by the polymerization of bicontinuous microemulsions containing polymerizable surfactants in addition to water and monomer [107]. Polymerizable surfactants, also called surfmers, are amphiphilic substances containing a polymerizable double bond [108]. A similar technology has been used to synthesize ion-conductive membranes [109], luminescence films [110], and polymer-inorganic nanocomposites [111]. 

The sensitivity of the luminescence IP s in the systems employed here decreases with increasing x-ray energy more strongly than in the case of x-ray film. Therefore, this phenomenon must be compensated by using thicker lead front and back screens. The specific contrast c,p [1,3] is an appropriate parameter for a comparison between IP s and film, since it may be measured independently of the spatial resolution. Since the absorption coefficient p remains roughly constant for constant tube voltage and the same material, it suffices to measure and compare the scatter ratio k. Fig. 2 shows k as a function of the front and back screen thickness for the IP s for 400 keV and different wall thicknesses. The corresponding measured scatter ratios for x-ray films with 0,1 mm front and back screens of lead are likewise shown. The equivalent value for the front and back screen thicknesses is found from the intersection of the curves for the IP s and the film value. 

Zinc compounds are generally colorless unless the other component, eg, chromate, is colored. The lack of color of most zinc compounds in visible light is a great advantage in that they do not color paint films, plastics, mbber, cosmetics, etc. However, when excited by various types of radiation and at various temperatures, zinc oxide, sulfide, selenide [1315-09-9], and related compounds exhibit luminescence, ie, they emit colored light (see Luminescent materials). Zinc-based phosphors can be produced in many colors, depending upon the added dopants. They are used in television tubes, luminescent glasses, and various specialty products. 

Figure 15-15. Relative luminescence intensity (open markers) compared with pristine MEH-PPV of composite films of MEH-PPV with CM and a series of TCNQ-like acceptors 1-6 (see Fig. 15-2 lor abbreviations) as a function of their reduction potentials at 80 K. Riglil-liand axis shows the ratio of the photoinduced absorption intensity of the bands at 1.34 and 1.22 eV (solid markers) (reproduced by permission of the American Institute of Physics from Ref. 1871).

Two practical advantages of luminescence species engulfed in antenna dendrimer scaffolds are apparent, namely their miscibility with organic media (solvents or/and resins) and their ability to form thin films. For example the lanthanide-cored dendrimer complexes described in this chapter can be regarded as organic-soluble inorganic luminescers. 

The PBE dendron has a glass transition at about 40 °C and is soluble in various organic solvents (e.g., THF, acetone, toluene). It is therefore a moldable, thermoplastic, film-forming material. This practical feature is maintained for the lanthanide-cored dendrimer complexes. The complexes are partially miscible with poly(methyl methacrylate), affording transparent luminescence compositions by mixing in solvent. 

The PPhE bearing the PBE dendron as the repeating side chains is also soluble in THF, whereas the rigid main chain itself does not dissolve in any solvent. The blue-luminescence dendron-grafted rigid polymer forms thin films by spin coating [18]. 

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