Poly , effect absorption spectra

Fig.7. Quadratic Stark effect spectrum of a poly(methylmetacrylate) film doped with an azobenzene-linked amphiphile C180AZ0C00H (solid line). Dotted line, broken line, and dash and dotted line show an absorption spectrum of the film, its first derivative, and second derivative, respectively.

Fig. 15. Rotatory artifacts that simulate Cotton effects at an absorption band. The dependence of the rotatory artifact on absorbance of p-cresol solutions placed in series with the same poly-L-glutamic acid solution is shown. The concentration of p-cresol was adjusted to give the total absorbance of chromophore plus polypeptide background that appears with each curve. The rotator, poly-L-glutamic acid, was at concentration of 0.5% at pH 7.0 in a 10-cm cell. The rotations are those actually observed, a, in degrees. The rotatory dispersion at Am 2 coincides almost exactly with that for the polypeptide alone, so that it has been omitted from the figure. At Am 4, an interference filter, /, with maximum transmission between 280 and 285 m/i, was placed in the optical path. The absorption spectrum, in arbitrary units, is typical of p-cresol plus poly-L-glutamic acid background. The emission spectrum is represented in arbitrary units, uncorrected for detector response. (Urnes et al., 1961a.)...

Fig. 1. The effect of increase in temperature on the absorption spectrum of long chain poly(ADP-ribose). An average chain length of 35 was used in the solution of 100 mAf Tris-HCl (pH 7.0) containing 1 Af NaCl...

Optical Lithography Rochford et al. obsenred similar results with laser sources operating at 442 and 514 nm. They found that for long exposure times, the optical absorption spectrum of poly(4BCMU) decreased uniformly in intensity, an effect they attributed to photooxidation. Patterns could be written into films, but the exposure times (hours) were excessive. 

More dramatic effects were observed with regioregular polyether-substituted polythiophenes. As reported by Levesque and Leclerc, chemically synthesized head-to-tail poly[3-oligo(oxyethy-lene)-4-methylthiophene] poly(5) led to ionochromic effects, with a clear isosbestic point on the UV-visible absorption spectrum, indicating the coexistence of long sequences of nonplanar and planar thiophene units [244, 245]. With the addition of a cation such as the main chain became twisted. However, in contrast to poly(4), this phenomenon was observed only with the polymer in solution. 

Yoshino, K., Onoda, M. and Sugimoto, R. "Effect of polymer elongation on the absorption spectrum of poly(3-alkylthiophene). , Jpn. /. Appl. Phys., 27, L2034-L2036. 

Similarly, an anion-selective fiber optic sensor was prepared using electropolymeiized Co(o-NH2)TPP. The polymeric layer was grown by cycling an ITO slide between -0.1 V and +1.2 (or 1.3 V) for a total of 100 cycles at 200 mV/s. The actual sensor was constmcted as describe above (Figure 4). The absorption spectrum of a poly[Co(o-NH2)TPP] slide changes in the presence of various concentrations of nitrite. As the nitrite concentration increases, a hyperchromic effect is seen due to the replacement of axial water ligands of the cobalt center with nitrite from the sample solution. These sensors were influenced by the ionic strength of the buffer solution in which they were used, and the solution pH also affected sensor response. In fact, a hydroxide interference was observed at pH > 6.5. 

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