Spectra polyvinyl alcohol

Another intermediate of the photolysis of TiO was observed in experiments with platinized particles (in the absence of polyvinyl alcohol). The spectrum shown in Fig. 22 is prraent immediately after the laser flash. The signal decays as shown by the inset in the figure. The rate of decay is not influenced by oxygen but is increased by oxidizable compounds such as Br ions in the solution. The broad absorption band in Fig. 22 with a maximum at 430 nm was attributed to trapped positive holes. Chemically, a trapped hole is an 0 radical anion. In homogeneous aqueous solution, 0 ... 

Radiation chemical studies were carried out with an acidic WO3 H O sol stabilized by polyvinyl alcohol It was found that (CH3)2COH radicals inject electrons into the colloidal particles. A long-lived blue color arose and the absorption spectrum showed a rising absorption above 700 nm. This absorption could have been produced by free electrons, although it could not be ruled out that the electrons reduced ions... 

I have a minor comment concerning the polyvinyl alcohol spectrum. The one shown (Figure 5) is similar to one obtained in our laboratory in 1973. Last year. Dr. Lana Sheer obtained a polyvinyl alcohol spectrum where the methlne resonance was resolved into a triplet of triplets. By studying the effect of temperature upon the spectrum and by tuning the spectrometer carefully, one sometimes obtains better hyperflne structure. 

Spectral data (Amax and AE, and e x 10 3) for the pyrimidine bases investigated in a few representative papers are collected in Table XXVIII. The absorption bands are denoted by the capital letters A, B, C, etc. In Table XXVIII we have listed the results of the vacuum ultraviolet measurements by Yamada and Fukutome428 (cf. also ref. 429), who measured the spectra of sublimed films of cytosine, thymine, uracil (and also of guanine and adenine) down to 120 nm at room temperature. Several remarkable absorption peaks were found below 190 nm in addition to the already known ones near 260 and 200 nm. A weak absorption at 230-240 nm in cytosine was not indicated in the sublimed films of the molecule,428 but was visible in the stretched polyvinyl alcohol film spectrum.432 Crewe et al.i3° studied the interactions of fast electrons with the five nucleic acid bases and measured the energy-loss spectra of 20 keV electrons transmitted through thin films of these bases. These last data are also listed in Table XXVIII for comparison with the other spectral findings. 

The spectrum of polyvinyl alcohol (PVA), -(CH2CHOH)n, was the subject of much early study [Thompson and Tor-kington (228)] Elliott, Ambrose, and Temple (53) Blout and Karplus (77) Ambrose, Elliott, and Temple (6) Glatt, Webber, Seaman, and Ellis (66) Glatt and Ellis (65)], but with only... 

Fig. 11. Infrared spectrum of oriented polyvinyl alcohol. — E perpendicular to stretching direction - — E parallel to stretching direction [Krimm, Liang, and Sutherland (704)]...

Infrared absorption spectrum of deuterated polyvinyl alcohol film. 

Figure 8. Carbon, Cls, spectra. Key a, from a polyvinyl alcohol homopolymer reference sample b, a spectrum of a modified glassy carbon surface corresponding to Fig. 7, spectrum e and c, the difference spectrum obtained by subtracting b from a, magnified 2X- (Reproduced, with permission, from Ref. 22. Copyright 1981, Pergamon Press.)...

Figure 9. A, a spectrum of polyvinyl alcohol corresponding to Figure 8, spectrum a. Conditions deconvoluted into component 1 (59.55%), BE — 284.1 and component 2 (40.45%), BE = 285.55 eV. B, a spectrum corresponding to Figure 8, spectrum b. Conditions deconvoluted using parameters from Figure 9 spectrum a, component 1 (53.32%), BE — 284.10 eV component 2 (34.17%), BE = 285.45 eV component 3 (9.43%), BE = 286.40 eV and component 4 (3.07%), BE — 287.50 eV all peaks have FWHM of 1.45 eV. The numbers indicated above in parentheses are the total area percentages for each component. XXX indicates spectra calculated from the individual components. (Reproduced, with permission, from Ref. 92. Copyright 1981, Pergamon Press.)...

However, in a recent publication, Shirinyan, Mnatsalianov, et al. (20) find that differences between the rates of vinyl acetate emulsion polymerisation observed with samples of similar polyvinyl alcohols manufactured by the same process In three different factories could be attributed to a condensation product of acetaldehyde derived from hydrolysis of residual vinyl acetate this gave rise to a conjugated ketone type ultra-violet spectrum and could be extracted from the polyvinyl alcohol under suitable conditions. This could be the uncontrolled factor which appears to have confounded nmuiy of the experiments reported here. Even more recently the same laboratory ( ) has reported that there Is an optimum sequence length of hydroxyl groups in the polyvinyl cdcohol-acetate block copolymer for polymerisation rate and dispersion stability. 

Spectra of Crystals Infrared Dichroism. The spectrum of a single crystal observed in polarized light depends upon the orientation of the crystal axes relative to the plane of polarization. A similar situation exists for macroscopically oriented high polymers, obtained by extruding or stretching polymeric materials such as nylon, polyvinyl alcohol, and polyethylene. Ellis and co-workers were the first to make systematic studies of IR dichroism in H bonded systems (604, 779, 780). Further attention was drawn to the method by Mann and Thompson (1334), Crooks (463), and Ambrose, Elliott, and Temple (595, 38, 589, 4). 

Electric-field-induced changes in the fluorescence spectrum of BCECF itself were also measured using electric field modulation spectroscopy [36,37]. For that purpose, a 0.4 ml portion of the aqueous solution (5 ml total) containing polyvinyl alcohol... 

Fig. 15. (A) Absorption, fluorescence and phosphorescence spectra of BChl a in vitro at 77 K spectra scaled for convenient presentation also note break of horizontal scale (B) Phosphorescence spectrum of quinone-depleted (-Q) and quinone-containing (+Q) Rb. sphaeroides reaction centers in polyvinyl-alcohol film at 22 K (C) Energy diagram for the components involved in triplet-triplet energy transfer with carotenoids. (A) and (B) and numerical values for the triplet-state energies of BChls a and b and the primary-donors of Rb. sphaeroides and Rp. viridis, i.e., [BChl a and [BChl bjj, respectively, are taken from Takiff and Boxer (1987) Phosphorescence spectra ofbacteriochlorophylls. J Am Chem Soc 110 4425.

Fig. 21. Top Experimental ( H)- C cross-polarization spectrum of freshly prepared poly-e-caprolactone nanospheres in an aqueous dispersion (wc—100 MHz, full proton decoupling). Five polymer signals ( P ) are detected within the given spectral range, other resonances can be assigned to the surfactant polyvinyl alcohol and small amounts of polyvinyl acetate. Bottom Corresponding ( H)- C cross-polarization spectrum of a solid bulk sample of poly-f-caprolactone under static conditions.

Fig. 9.11 Transient absorption spectrum of trapped electrons in 6.3 X 10 M TiOi colloids in solutions containing 5 x 10" M polyvinyl alcohol (hole acceptor) at pH 10 after a laser flash. Insert time profile of the absorption. (After ref. [44])...

In the polymer industry, packing material, laminates including multilayer films, pellets or molded products can be analyzed by NIR. Even polymer latex particles with up to 99 % water content may be analyzed. NIR provides information about reaction mechanisms, polymerization, crystallinity, orientation, water content and hydrogen bonding, even during the process of polymer manufacture. For example the disappearance of the double bonds in polyethylene and polypropylene can be monitored. In the NIR spectrum C=C bonds lead to a combination band at about 4740 cm and a first overtone at about 6170 cm NIR spectroscopy is applied to characterize ester-, nitrile-, or amide-based acrylic and methacrylic polymers. Other examples are the identification of polyvinylchloride, polyvinyl alcohol and polyvinyl acetates or the analysis of polymerization in epoxy and phenolic resins. 

A macroscopic PbS crystal has a band gap of 0.41 eV. Because of the small effective mass of the electrons and holes ( e,eff = h,efF = 0.09 X OTg), Strong size-quantization occurs. The absorption spectrum of an aqueous suspension (of polyvinyl alcohol-capped) PbS nanocrystals, 6.5 nm in diameter (see TEM picture) is shown in Fig. 13. The HOMO-LUMO optical transition occurs at 2.1 eV, and two other absorption peaks are seen at 3.2 and 4.3 eV. When a gold electrode is immersed in this colloidal solution, PbS nanocrystals... 

A surface method of measurement of a sizing agent (partly hydrolysed polyvinyl alcohol) on the warp yam substrate (polyester/cotton) using NIR diffuse reflectance spectroscopy has been described (337). A partial least-squares (PLS) modelling procedure used a frequency segment of the NIR spectrum that is most sensitive to changes in size concentration relative to the warp yarn. 

The copolymer exhibits the same solubility profile as that for polyvinyl alcohol and the visible absorption spectrum of its DMSO solution shows a broad absorption peak with Amax near 400 nm due to the it— It transition of the thiophene oligomer. Elemental analysis data, however, indicates that less than 1% of the thiophene oligomer is anchored to polyvinyl alcohol. 

EPR spectrum of Cu(II) complex described. 5 =2.0045,2.053. DAP = 0.10 M dodecylammonium propanoate. ) da(N)/dr=0.215pTK-MnTHF. ) Measurement of in 15 solvents. Variation of % vs. solvent polarity and T measured. Study of interaction with surfactant vesicles. ) Temperature dependent study. Measurements in HjOF polyvinyl alcohol gel. ) Measurement of rotational diffusion. Formation of dimers at low temperature measurements at 9 and 35 GHz. ) da(N)/d7 =0.109pTK-MnCCl4. ... 

FIGURE 20. lET spectrum of polyvinyl alcohol. Reprinted with permission from Reference 28. Copyright 1985 Butterworth Scientific Ltd. 

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