Spectrum optical absorption

Knickelbein M B and Menezes W J C 1992 Optical response of small niobium clusters Rhys. Rev. Lett. 69 1046 Ceilings B A, Athanassenas K, Lacombe D, Rayner D M and Hackett P A 1994 Optical absorption spectra of AUy,... 

Alvarez M M efa/1997 Optical absorption spectra of nanocrystal gold molecules J. Phys. Chem. B 101 3706... 

Computed optical properties tend not to be extremely accurate for polymers. The optical absorption spectra (UV/VIS) must be computed from semiempiri-cal or ah initio calculations. Vibrational spectra (IR) can be computed with some molecular mechanics or orbital-based methods. The refractive index is most often calculated from a group additivity technique, with a correction for density. 

Cm ORINE OXYGEN ACIDS AND SALTS - Cm OROUS ACID, Cm ORITES, AND Cm ORINE DIOXIDE] (Vol 5) Optical absorption spectra... 

Eig. 27. Optical absorption spectra of thin, 1 p.m-films of novolac, polyhydroxystyrene and polyacrylate polymers. The novolac resin is transparent only above 300 nm. While polyhydroxystyrene also absorbs strongly below 300 nm, it exhibits a region of adequate transparency centered near 248 nm. The... 

The optical absorption spectra of Pu ions in aqueous solution show sharp bands in the wavelength region 400—1100 nm (Fig. 4). The maxima of some of these bands can be used to determine the concentration of Pu ions in each oxidation state (III—VI), thus quantitative deterrninations of oxidation—reduction equiUbria and kinetics are possible. A comprehensive summary of kinetic data of oxidation—reduction reactions is available (101) as are the reduction kinetics of Pu + (aq) (84). 

The changes in the optical absorption spectra of conducting polymers can be monitored using optoelectrochemical techniques. The optical spectmm of a thin polymer film, mounted on a transparent electrode, such as indium tin oxide (ITO) coated glass, is recorded. The cell is fitted with a counter and reference electrode so that the potential at the polymer-coated electrode can be controlled electrochemically. The absorption spectmm is recorded as a function of electrode potential, and the evolution of the polymer s band stmcture can be observed as it changes from insulating to conducting (11). 

A brief review is given on electronic properties of carbon nanotubes, in particular those in magnetic fields, mainly from a theoretical point of view. The topics include a giant Aharonov-Bohm effect on the band gap and optical absorption spectra, a magnetic-field induced lattice distortion and a magnetisation and susceptibility of ensembles, calculated based on a k p scheme. 

In Sec. 2 the effective mass equation is introduced and the band structure is discussed with a special emphasis on an Aharonov-Bohm effect. Optical absorption spectra are discussed in Sec. 3. A lattice instability, in particular induced by a magnetic field perpendicular to the tube axis, is discussed in Sec. 4 and magnetic properties of ensembles of CNTs are discussed in Sec. 5. 

Fig. 6. Calculated optical absorption spectra of a metallic CNT in a magnetic flux. In the case that the electric field is parallel to the axis (left), the absorption exhibits a distinct AB effect. In the case of the perpendicular polarisation (right) the depolarisation effect suppresses the absorption almost completely.

Figure 15-3. la) Optical absorption spectra of MEH-PPV and C. (b) Optical absorption spectra of MEH-PPV/Cft(i films with different concentrations of C j (reproduced by permission of the American Physical Society from Ref. (381). 

From the optical absorption of two different hexaphenyl films, one with its chains predominantly standing upright on the substrate, the other with the chains randomly distributed in all orientations, similar structure property relations can be concluded [139]. By comparing the calculated absorption coefficient [139J perpendicular to the chains with the observed optical absorption spectra of both films we see that the optical absorption, plotted in Figure 9-9, in the visible and... 

Asmus et al. unambiguously identified a variety of [R2S.. SR2] radical cations in solution and measured their optical absorption spectra using pulse radiolysis techniques [133]. They proposed that the spectrum of [H2S. .SH2] arises from the transition in the three-electron S.. S... 

The optical absorption spectra and the first reduction potentials are virtually independent of the number of pyrene units present in the molecule, as a result of the specific stereoelectronic situation. Since the orbital coefficients of the bridgehead centers are almost zero, the rings are electronically decoupled. Thus, oligopyrenes differ significantly from oligo(pflrfl-phenylene)s (OPVs). 

Idrobo, J.C., Walkosz, W, Yip, S.F., Ogiit, S Wang, J. and Jellinek, J. (2007) Static polarizabilities and optical absorption spectra of gold clusters (Aun, n = 2-14 and 20) from first principles. Physical Review B - Condensed Matter, 76, 205422-1-205422-12. 

Liu, J., Maaroof, A.I., Wieczorek, L. and Cortie, M.B. (2005) Fabrication of hollow metal nanocaps and their red-shifted optical absorption spectra. Advanced Matenals, 17, 1276-1281. 

The optical absorption spectra of sulfonyl radicals have been measured by using modulation spectroscopy s, flash photolysis and pulse radiolysis s techniques. These spectra show broad absorption bands in the 280-600 nm region, with well-defined maxima at ca. 340 nm. All the available data are summarized in Table 3. Multiple Scattering X, calculations s successfully reproduce the experimental UV-visible spectra of MeSO 2 and PhSO 2 radicals, indicating that the most important transition observed in this region is due to transfer of electrons from the lone pair orbitals of the oxygen atoms to... 

Figure 21. Room-temperature optical-absorption spectra of various digestively ripened Au colloids prepared by the inverse-micelle method. For comparison, the spectrum of the as-prepared colloid is also displayed. (Reprinted with permission from Ref [49], 2002, American Chemical Society.)...

The optical absorption spectra of Au-implanted silica samples annealed in air or Ar for 1 h at different... 

Figure 7. Optical absorption spectra of Au-implanted silica samples atmealed in air (a) or Ar (b) for 1 h at different temperatures, (c) Nonlinear fit (empty circles) to the optical absorption spectrum of the sample annealed at 900 °C in air, from which the average cluster diameter is obtained and compared to the TEM measured one, (d) Evolution of the optical spectra of Au-...

The TEM data have been used to simulate, in the frame of the Mie theory and Maxwell-Garnett effective medium approximation [15], the optical absorption spectra of the sample implanted with 5 x lO Au /cm. The results are reported in Figure 8(c). In the first model used to describe... 

Figure 17. Optical absorption spectra of the polyimide implanted with 5x 10 Au m in presence of dry air and of methanol vapor (6000 ppm). Inset optical absorption difference calculated taking into account both spectra. (Reprinted from Ref. [68], 2005, with permission from Elsevier.)...

Figure 9 summarizes the optical absorption spectra of the aqueous solutions or solid film of 1-9 and sodium gold(I) thiomalate (SGT) at ambient temperature. 

Fig. 31. Optical absorption spectra of PbS colloids (1.0 X 10 M) in acetonitrile a) particle diameter 50-200 A b) particle diameter 20-30 A ...

Let us now consider MMCT for the case in which the donating ion is a lanthanide ion with a partly filled 4/ shell M(/")M(d°)CT. The trivalent lanthanide ions with a low fourth ionization potential are Ce, Pr ", Tb ". Their optical absorption spectra show usually allowed 4f-5d transitions in the ultraviolet part of the spectrum [6, 35]. These are considered as MC transitions, although they will undoubtedly have a certain CT character due to the higher admixture of ligand orbitals into the d orbitals. In combination with M(d°) ions these M(/") ions show MMCT transitions. An early example has been given by Paul [36] for Ce(III)-Ti(IV) MMCT in borosilicate glasses. The absorption maximum was at about 30000 cm ... 

In amorphous semiconductors, information about the width of the band tail states (or disorder) may also be extracted from the optical absorption spectra. For photon energies near bandgap energy, the optical absorption coefficient of amorphous semiconductors exhibit an exponential dependence on the photon energy, following the so-called Urbach relationship ... 

Figure 5. Optical absorption spectra of a thin film of...

In order to follow progress of elimination, reactions were also performed on thin films in a special sealed glass cell which permitted in situ monitoring of the electronic or infrared spectra at room temperature (23°C). Typically, the infrared or electronic spectrum of the pristine precursor polymer film was obtained and then bromide vapor was introduced into the reaction vessel. In situ FTIR spectra in the 250-4000 cm-- - region were recorded every 90 sec with a Digilab Model FTS-14 spectrometer and optical absorption spectra in the 185-3200 nm (0.39-6.70 eV) range were recorded every 15 min with a Perkin-Elmer Model Lambda 9 UV-vis-NIR spectrophotometer. The reactions were continued until no visible changes were detected in the spectra. 

Figure 4. Optical absorption spectra of sol-gel derived Ti02 coating films with different thicknesses.

Figure 3.70 Room temperature optical absorption spectra of a 45(X)A-lhick film of neutral polypyrrole doped with at0.03 torr. (a) before exposure to I2, conductivity <10 6fl 1cm"1 (b) after 2 minutes I2 exposure, conductivity 4.8 ft em 1 (c) after 7 minutes exposure, conductivity 6,7 ft em 1 (d) after 22 minutes I2 exposure, conductivity 32ft cm The three structures seen on the low-energy side of (a) (c) arc possibly artifacts due to interference effects in the films. From Pfluger et at. (1983).

Figure 5. Comparison of the optical absorption spectra of cobalt(III) porphyrin ir-cation radical species with those of catalase compound / and horseradish peroxidase compound L The ground states of the bromide and perchlorate species are 2A lu and 2Agu, respectively.

Figure L Optical absorption spectra of well-isolated Ag atoms in Ar, Kr, and Xe matrices (Ag/inert gas 1/105) at 10-12 K. (Reproduced from Ref. 30. Copyright 1980, American Chemical Society.)...

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