Poly luminescence spectroscopy

The cadmium chalcogenide semiconductors (qv) have found numerous appHcations ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, teUuride, and oxide, are used as phosphors in luminescent screens and scintiUation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recently attracted attention as a third-order, nonlinear optical switching material (see Nonlinear optical materials). DiaLkylcadmium compounds are polymerization catalysts for production of poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl, they catalyze the polymerization of ethylene and propylene. 

J.K. Herrema, P.F. van Hutten, R.E. Gill, J. Wildeman, R.H. Wieringa, and G. Hadziioannou, Tuning of the luminescence in multiblock alternating copolymers. 1. Synthesis and spectroscopy of poly[(silanylene)thiophene]s, Macromolecules, 28 8102-8116, 1995. 

Of the various techniques routinely available, IR and 13C NMR spectroscopy usually provide the most valuable information in terms of the determination of the most appropriate valence description (A-D, Chart 1) of the carbon fragment. Mossbauer spectroscopy has also been used with good effect with iron-containing poly-carbon complexes.89 This solution-based work is complemented by a significant number of solid-state structural studies, which are described in greater detail below. Electronic spectroscopic methods, including luminescence methods, have been used to probe the electronic structures of a small number of poly-yndiyl complexes and polymers.288 315 340 342 377 380 Selected IR, 13C NMR, and UV-vis data have been given in Tables I-VIII, above. 

The next question is how side-chain substitutions and skeleton conformations affect the band structures of polysilanes. Side chains provide two interesting effects (7) band gap reduction caused by substitution of larger alkyl side chains and skeleton-side chain interaction (i.e., (j-tt mixing) in aryl poly silanes. This interaction was confirmed by UV photo spectroscopy (UPS) (8-9) and photoabsorption and luminescence measurements (iO, 11). Skeleton conformations are related to thermochromism (12-17). The ab initio... 

In this last study it was shown that the luminescence emission from wool keratin is very similar to that from tryptophan in a solid poly(vinyl alcohol) film, which thus provides a useful model system. In both cases the triplet state could be readily studied both at 77 and ambient temperatures by emission and absorption spectroscopy. 

Radioluminescence spectroscopy has been used to examine molecular motion, solubility, and morphology of heterogeneous polymer blends and block copolymers. The molecular processes involved in the origin of luminescence are described for simple blends and for complicated systems with interphases. A relatively miscible blend of polybutadiene (PBD) and poly(butadiene-co-styrene) and an immiscible blend of PBD and EPDM are examined. Selective tagging of one of the polymers with chromophores in combination with a spectral analysis of the light given off at the luminescence maxima gives quantitative information on the solubility of the blend components in each other. Finally, it is possible to substantiate the existence and to measure the volume contribution of an interphase in sty-rene-butadiene-styrene block copolymers. 

Peptides are known to show some specificity toward metal binding, as was shown by titration experiments nsing H-NMR [7,8], potentiometry [9], luminescence measnrements [10], infrared (IR), circular dichroism (CD), and ultraviolet (UV spectroscopies [11]. Poly-L-aspartic acid binds to metals such as Eu, Ce, La +, Cu ", and Pb ", and acts as a corrosion inhibitor for steel and iron. This property has been ascribed to the carboxylate side chain of aspartic acid [12,13]. 

NN = polypyridyl ligands and L = stilbene-like ligands, in acetonitrile solution and in poly(methyl methacrylate) (PMMA) polymer film exhibited hypsochromic shifts as the medium rigidity increases due to the luminescence rigidochromic effect. Time-resolved IR (TRIR) spectroscopy, in combination with other techniques, characterized the excited-state electronic properties of the fac-[Re(CO)3(phen) (bpe)]PFa complex, where bpe is l,2-bis(4-pyridyl)ethylene. 

Wallndfer et al. [963] investigated various anellated and alkylated polythiophenes [(polyisothianaphthene (PITN), polyison-aphthothiophene (PINT), poly(3-octylthiophene) (POT)] prepared by electropolymerization with resonance Raman spectroscopy at various laser wavelengths. " The spectrum of POT is dominated by a strong luminescence (which is related to some of the possible appUcations of this material). The main peak is around 1460 cm ... 

S. Luzzati, P. Elmino, and A. Bolognesi. Luminescence excitation spectroscopy of highly oriented poly(3-octylthiophene) - polyethylene blends. Synthetic Metals 76, 23-26 (1996). 

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