Absorption spectrum extinction coefficient

D. gigas AOR was the first Mo-pterin-containing protein whose 3D structure was solved. From D. desulfuricans, a homologous AOR (MOD) was purified, characterized, and crystallized. Both proteins are homodimers with-100 kDa subunits and contain one Mo-pterin site (MCD-cofactor) and two [2Fe-2S] clusters. Flavin moieties are not found. The visible absorption spectrum of the proteins (absorption wavelengths, extinction coefficients, and optical ratios at characteristic wavelengths) are similar to those observed for the deflavo-forms of... 

In a transition to a higher electronic level, a molecule can go from any of a number of sub-levels—corresponding to various vibrational and rotational states— to any of a number of sub-levels as a result, ultraviolet absorption bands are broad. Where an infrared spectrum shows many sharp peaks, a typical ultraviolet spectrum shows only a few broad humps. One can conveniently describe such a spectrum in terms of the position of the top of the hump (A x) and the intensity of that absorption the extinction coefficient). 

Experimental data were used to calculate the absorption spectrum of a monolayer, the effective scattering, absorption, and extinction coefficients. The optical properties of a single granule were theoretically obtained with Mie theory for the homogeneous and two-layered spheres with regard to size-dependence of Cu optical constants in the frame of the model of a mean free path electron limitation... 

Ultraviolet Spectra. Only one absorption above 300 nm is clearly visible in the UV spectrum of amides in NH3 solution. A second band at 240 nm or shorter wavelengths is obscured by the onset of the absorption of the solvent [41, 42]. At a given temperature the absorption shifts to higher wavelengths as the size of the cation increases from Li to K and then remains constant. A similar solvation of the larger cations (K, Rb, Cs) indicates electrostatically associated ion pairs without appreciable perturbation of the solvent sphere around the anion. The smaller cations, however, have a stronger influence on the solvent sphere of the amide ion [43]. The positions of the maxima of the absorption and extinction coefficients... 

Percentage of substitution on the polymers. Values obtained from GPC using polystyrene as the standard. Values obtained from Vapor Pressure Osmometry, in toluene, 60 C. absorption maximum measured in THF. Values obtained from deconvoluted spectrum. Extinction coefficient in cm M". SSample was washed with MeOH to remove magnesium salts. 

The ultraviolet absorption spectrum of thiazole was first determined in 1955 in ethanolic solution by Leandri et al. (172), then in 1957 by Sheinker et al. (173), and in 1967 by Coltbourne et al. (174). Albert in 1957 gave the spectrum in aqueous solution at pH 5 and in acidic solution (NHCl) (175). Nonhydroxylic solvents were employed (176, 177), and the vapor-phase spectrum was also determined (123). The results summarized in Table 1-15 are homogeneous except for the first data of Leandri (172). Both bands A and B have a red shift of about 3 nm when thiazole is dissolved in hydrocarbon solvents. This red shift of band A increases when the solvent is hydroxylic and, in the case of water, especially when the solution becomes acidic and the extinction coefficient increases simultaneously. 

The reduced symmetry of the chromophore, which still contains 187t-electrons and is therefore an aromatic system, influences the electronic spectrum which shows a bathochromic shift and a higher molar extinction coefficient of the long-wavelength absorption bands compared to the porphyrin, so that the photophysical properties of the chlorins resulting from this structural alteration render them naturally suitable as pigments for photosynthesis and also make them of interest in medical applications, e.g. photodynamic tumor therapy (PDT).2... 

A useful measure of the strength or intensity of the colour of a dye is given by the molar extinction coefficient (e) at its 2max value. This quantity may be obtained from the UV/visible absorption spectrum of the dye by using the Beer-Lambert law, i.e. 

Compounds containing doubly bonded tin are highly colored due to a strong absorption in the visible spectrum (77-77 transition of the double bond). The extinction coefficients of the distannene [[(Me3Si)2CH]2Sn]2 (entry 3, Table VII) were found to depend on concentration and temperature5 that for the absorption at 332 nm increases with dilution while that for the 495 nm absorption decreases. This suggests that the absorptions arise from two different species, presumably the distannene and the stannylene. By comparison with the other absorption maxima of doubly bonded tin compounds, the absorption at 495 nm is probably that of the distannene. 

Dihydroxy-4 -vinylbenzophenone was converted to a homopolymer of inherent viscosity 0.57 djfc/g by polymerization with AIBN in dimethylformamide. The UV spectrum of the polymer showed the three absorption maxima characteristic of 2,4-dihydroxy b enz ophenones (at 324, 292 and 248 nm), although the extinction coefficient was depressed in comparison with the 4 -ethyl analogue. 

The intensity of absorption gives the product G , where G is the observed yield and is the molar extinction coefficient. The absolute value of was determined by Fielden and Hart (1967) using an H2-saturated alkaline solution and an alkaline permanganate-formate solution, where all radicals are converted into Mn042. They thus obtained = 1.09 x 104 M- cm1 at 578 nm, which is almost identical with that obtained by Rabani et al. (1965), who converted the hydrated electron into the nitroform anion in a neutral solution of tetrani-tromethane. From the shape of the absorption spectrum and the absolute value of at 578 nm, one can then find the absolute extinction coefficient at all wavelengths. In particular, at the peak of absorption, (720)/ (578) = 1.7 gives at 720 nm as 1.85 X 104 M 1cm 1. 

Farhataziz et al. (1974a, b) studied the effect of pressure on eam and found that as the pressure is increased from 9 bar to 6.7 Kbar at 23° (1) the primary yield of e decreases from 3.2 to 2.0 (2) hv increases from 0.67 to 0.91 eV (3) the half-width of the absorption spectrum on the high-energy side increases by 35% and (4) the extinction coefficient decreases by 19%, which is similar to eh. The pressure effects are consistent with the large volume of ean (98 ml/M), whereas the reduction in the observed primary yield at 0.1 ps is attributable to the reaction eam + NH4+. Some of the properties of eam have been discussed by several authors in Solvated Electron (Hart, 1965). 

The spectral properties of these derivatives are similar to native rhodamine. The excitation maximum occurs at about 543 nm and its emission peak at 567nm, producing light in the orange-red region of the spectrum. The extinction coefficient of tetramethylrhodamine-5-(and-6)-iodoacetamide in methanol at its wavelength of maximum absorptivity, 542 nm, is 81,000M-1cm-1. 

The ultraviolet spectrum of pseudoephedrine hydrochloride in ethanol was obtained with a Beckman ACTA CIII ultraviolet spectrophotometer and is shown in Figure 3.4 Pseudoephedrine hydrochloride exhibits absorption maxima at 208, 251, 257, and 264 nm with extinction coefficients of 8300, 161, 201, and 161, respectively. 

The electronic spectrum of the fractions containing the pure tridehydro [18]annulene exhibits the strongest absorption maximum (in benzene) at 342 nm. (e 155,000) and the spectroscopic yield, based on the molar extinction coefficient, is 1.17 g. (2.40% from 1,5-hexadiyne). The yield of tridehydro[18]annulene in the mixed fractions, based on the 342 nm. maximum,is 0.27g.(0.55%). The tridehydro [18]annulene is best stored in solution in the refrigerator. 

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