Poly , ultraviolet spectrum

Fig. 4. Optical rotatory dispersion of helical synthetic polypeptides in the ultraviolet spectrum. Poly-y-benzyl-L-glutamate in dioxane solution, --- poly-L-...

Figure 10. CD spectra of poly(n-hexylisocyanate) (poly-85) dissolved in optically active solvents at 20 °C. Ultraviolet spectrum (bottom) shown only for (A)-2-chlorobutane (polymer concentration 1.9 mg/mL). (Reprinted with permission from ref 171. Copyright 1993 American Chemical Society.)...

Figure 2. Visible-Ultraviolet Spectrum of Poly(butadiyne)...

The absorption and emission of radiation in the near ultraviolet (UV) and visible regions of the electromagnetic spectrum are associated with electronic (and associated vibronic) transitions involving n- and/or n-electron systems of molecules. Synthetic and natural polymers absorb in the UV region and particularly strong absorption spectra are recorded for polymers containing aromatic and heteroaromatic groups (e.g., poly(styrenes), poly(vinyl naphthalenes), poly(vinyl carbazoles)). 

Only one ESR study on the radicals formed by ultraviolet light in poly (1-butene) has been reported (4, 5). In this work ethyl radicals giving a sextet spectrum with a hyperfine splitting constant of 27 gauss... 

The ESR spectrum of radicals in poly(4-methyl-l-pentene) induced by ultraviolet light 4,5) is composed of a sharp quartet with the hyper-fine splitting constant of 22.5 gauss and a broad quartet. The sharp component has been attributed to methyl radicals (XI) while the broad component could be caused by polymer radicals of structures XXIII and/or XXIV. 

The absorption spectrum for a typical stabilizer of this type, 2-hydroxy-4-dodecyloxybenzophenone, is shown in Figure 8 (10) along with that of poly (ethylene—CO). Over the near ultraviolet range, the absorption coefficient of the stabilizer is much greater than that of the polymer, and even at low concentrations the stabilizer will absorb most of the light, thereby protecting the polymer. 

Because of instrumental limitations, most optical rotatory measurements upon polypeptides and proteins have thus far been made in the near ultraviolet and visible regions of the spectrum, a range over which the Drude and Moffitt equations are valid. For this reason, attention will henceforth be directed to featureless curves of the type shown in Fig. 1. The immediate concern will be to describe the optical rotatory properties of synthetic polypeptides with respect to conformation in order that these attributes may be subsequently employed in the analysis of protein structure. Synthetic poly-... 

For poly(9,9-di-n-octylfluorene) (PFO), which is deemed a model polymer in PFs, Janietz and coworkers reported its HOMO (equivalent to ionization potential, Ip) and LUMO (equivalent to electron affinity, Ea) levels as 5.8 and 2.12 eV below the vacuum level, respectively, as determined from cyclic voltammetry (CV) measurements of PFO thin solid film [11] as shown in Fig. la. However, the HOMO and LUMO levels provide a larger band gap of 3.68 eV than the value of 2.95 eV determined from the onset position in the ultraviolet-visible (UV) absorption spectrum of PFO film. If the band gap is taken as 2.95 eV and the HOMO level as 5.8 eV, the LUMO level of PFO... 

Tsuij et al. (104, 105) observed ESR spectra of this polymer after UV irradiation. When poly 3,3 bis(chloromethyl)oxetane was irradiated at -196° C in a nitrogen atmosphere with ultraviolet light, a triplet spectrum with a coupling constant of about 21 gauss was observed, as shown in Fig. 20a. This spectrum was attributed to free radicals... 

The electronic and chemical structure of poly(67) was studied experimentally by X-ray and ultraviolet photoelectron spectroscopy, and theoretically by quantum-chemical calculations [122]. X-ray spectroscopy showed that the thin films were chemically pure with no oxygen present. The remarkably well-resolved S2p spectrum indicated the quality of the polymer material to be excellent (minimum of chemical and spatial... 

We therefore carried out a series of studies on the circular dichroism spectrum of poly(i -oxypropylene) in a number of solvents in the vacuum ultraviolet region under the cooperation with W.C. Johnson, Oregon State University. In the circular dichroism(CD) spectra of poly(/ -oxypropylene), two CD bands were observed for cyclohexane, acetonitrile, and trifluoroethanol(TFE) solutions. 

Fig. 4.9. Change in the ultraviolet absorption spectrum of poly(hexamethylene-a-truxillamide) during UV irradiation at 224 nm [2088]. (Reproduced with permission from [2088] published by John Wiley Sons, Inc., 1971.)...

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