Light absorption spectrum

Comparison of the light absorption spectra of the aromatic amino acids tryptophan and tyrosine at pH 6.0. The amino acids are present in equimolar amounts (10 3 m) under identical conditions. The measured absorbance of tryptophan is as much as four times that of tyrosine. Note that the maximum light absorption for both tryptophan and tyrosine occurs near a wavelength of 280 nm. Light absorption by the third aromatic amino acid, phenylalanine (not shown), generally contributes little to the spectroscopic properties of proteins. 

In Sect. 6, the complex formation in the crystalline phase of PVA which is caused at very high iodine concentrations in the soaking solution was studied In this case, the X-ray diffraction completely changes from that observed at low iodine concentrations, and both resonance Raman and visible light absorption spectra demonstrate that the I3- mode complex is formed in the crystalline phase. The iodine absorbed in the crystalline phase forms a co-crystal with PVA whose model is proposed on the basis of the equatorial X-ray diffraction. However, it should be noted that the adsorption does not occur uniformly throughout a crystal, as suggested by the extraordinary broadening of the X-ray diffraction. The structure of the complex formed in the crystalline phase is... 

FIGURE 20. Visible light absorption spectra of PSI solutions and PSI tpy-ClsNQ ITO. 

The main purpose of the international research is to inhibit charge recombination and to extend catalyst light absorption spectra to the visible region. 

Photoelectrochemical measurements also provide an approach to the determination of electrophysical characteristics of diamond. In addition to the threshold energies of electron phototransitions, determined by the analysis of the photocurrent action spectra (Section 7), the diffusion length of minority carriers in polycrystalline diamond films was estimated (at 2 to 4 pm) by comparing light absorption spectra and open-circuit potential spectra [171],... 

In vivo light absorption spectra (400-700 nm) were recorded with a Varian-Cary spectrophotometer equipped with an integrating sphere. Samples were taken to an approximate optical density of 0.1. Data were corrected for scattering by subtracting a baseline value as measured at 725 nm. The spectrally averaged, chlorophyll a specific absorption cross section (aph, m2 mg Chi a-1) was calculated as follows ... 

Figure 9.5. Visible absorption spectra of PVP film with various viologens exposed to UV light. Absorption spectra given qualitatively as for absorbance in order to make comparisons easier.

Chemical structures, thermal degradation behaviour and light absorption spectra are shown for ethyl-2-cyano-3,3-diphenylacrylate (Uvinul 3035), 2-ethylhexyl-2-cyano-... 

Electronic Absorption Spectroscopy. Theoretical considerations of the light absorption spectra of /3-carotene (189) and related polyenes have been presented.A method has been devised for describing the shapes of the absorption spectra of polyenes such as -carotene and retinyl acetate as lognormal distribution curves.A new absorption band is seen in the spectrum of jS-carotene acting as electron donor in charge-transfer complexes.The triplet-triplet... 

Fig. 2. Absolute and difference light absorption spectra of cytochrome c peroxidase and Compound ES at pH 7 and 20° (-----------------) enzymes and (—) + CjHiOOH.

Fig. 9. Light absorption spectra of hemiglobin (Hi) at varying pH. Preparation of Hi from HbOj by means of excess KaFe(CN)e. Recorded with a Beckman DB spectrophotometer, layer thickness 0.007 cm.------------ pH 9.12 by means of 0.2 N NaOH ...

Fig. 9. Light absorption spectra of OB3b MMOH in presence of phenol or p-CN-phenol at pH 7.2. Difference optical spectra at 4°C and 0.1 M MOPS pH 7.2 of 25 mM phenol...

Fig. 14. Light absorption spectra of oxidized and reduced PAP from rat osteoclast.

The large dependence of the Soret-band Cotton effects on the state of oxidation observed in cytochromes c from various mammalian and other sources could not be seen with cytochrome C4 from Azotobacter vinelandii. Its CD spectrum in the range 240—440 nm is rather similar to that of the heme undecapeptide from horse heart cytochrome c (see below). It appears that CD spectra of cytochromes are a better means of characterization and classification than light-absorption spectra (214). 

Menningen et al. (1995a) have studied the CH and CH3 densities in a hollow-cathode dc-discharge CVD reactor. They observed the white-light absorption spectra of CH using either the (0,0) band near 432 nm or the... 

Chemical Reactivity. Among other things, reactivity plays a vital role in determining fate of pollutants in the environment. A prototype computer system to estimate reactivity of systems based on stmcture, SPARC (SPARC Performs Automated Reasoning in Chemistry), is described (242). As of this writing, procedures for hydrolysis rate constants, ionization uv—vis light absorption spectra, and several physical properties have been developed for SPARC. 

Millaud and co-workers (12) have examined several of these polymers, particularly the polymer from 2-methyl-l,4-phenylenediamine and terephthaldehyde, for viscosity-light scattering molecular weight relationships, persistence length, light absorption spectra, and the formation of lyotropic solutions in sulfuric acid. 

Electronic Absorption Spectroscopy. Doping with iodine and SO3 had a significant effect on the absorption spectrum of /3-carotene. Triplet-triplet absorption spectra have been obtained for six carotenoids, e.g. canthaxanthin carotene-4,4 -dione (181)] in benzene, " and bimolecular rate constants for energy transfer from singlet oxygen to carotenoids evaluated. U.v. spectra of retinal, retinyl acetate, and axerophtene (182) in solid films have been determined. Several papers discuss the light absorption spectra of retinal derivatives as rhodopsin models. ... 

---