Extinction coefficient measurement

C. Relative Extinction-Coefficient Measurements for Naked Silver... 

Solubility of Americium Hydroxide. Solutions containing greater than 10-6 M americium were examined by spectrophotometry to verify whether or not polymers were present. The molar extinction coefficient measured for the 503 nm absorption band was found to remain constant at e = 390 5 for all investigated solutions at pH = 3 6. Spectra recorded up to 850 nm in this pH range show the typical absorption bands of the Am3+ ion, which are similar to those observed in a dilute HCIO4 solution, without broadening or displacement. The concentration of americium ions in equilibrium solutions, [Am]s, is, therefore, considered a composite of only monomer species ... 

Table 4. Standard potentials of some aromatic and heteroaromatic compounds, E°, the wavelength corresponding to maximum absorption, -imax, the extinction coefficients measured by means of the dip probe are given by fiprobe (see Section 2.6.3 and Ref [65] for details), and those by the flow technique are given by enow...

UV Measurements. For the UV extinction coefficient measurements, absorption spectra were made with a Bausch and Lomb 303 or a Cary Model l4 spectrophotometer. 

For At, we can use the extinction coefficient measured for the model compound, p-benzoyl phenyl isobutyrate (5. 7 x 10 1-mole -cm ) and then use the experimental Aa s to compute the E/ABP phase sizes, (d/Z). These are shown in Table VI. 

Anomalies in extinction coefficient measurements. Anal. Chem. 26,860-878. Granger, G. W. 1952. Objectivity of colour preference. Nature 179, 778. 

To that end the use of FID detection has considerable advantages cfr. ref. [38]). The PTV-CT-GC-FID method is useful mainly for qualitative analysis and rapid screening. For quantitative analysis the reproducibility (now within about 20%) needs to be improved. Scrivens et al. [38] have proposed the use of a TD-GC-MS/FID set-up in which the concentrator gas flow is split to an FID detector for real-time monitoring of the evolution of volatiles and the measurement of the total amount of sample trapped into a sorbent trap kept at room temperature for further GC-MS processing. Quantitation is facilitated by the ability to inject a standard into the wide bore trap during volatile collection. In on-line TD-GC-FTIR-FID quantitative analysis can be made on the basis of extinction coefficients measured on standards [39]. 

Goldring et al. in their treatment of anomalies in extinction coefficient measurements, presented both a report of the precision and accuracy of the Beckman DU and the conditions under which it achieves optimum performance. Caster reported on the variability of this spectrophotometer. 

CD is a small effect. Ae/e, tire ratio of tire difference in circularly polarized extinction coefficients, Ae = Aj - Ej, to total absorjrtion, s = + Ej ), is typically only about 10 - 10 . Being so small, tire measurement of CD witli... 

Measurements were performed employing a Perkin Elmer X2, 5 or 12 UV-Vis spectrophotometer at 25 O.r- C. Equilibrium constants were determined by measuring the extinction coefficient at a suitable wavelength of the partially complexed dienophile (y,.hs) as a function of the concentration of... 

Absorption Spectra, of Aqueous Ions. The absorption spectra of Pu(III) [22541-70 ] Pu(IV) [22541 4-2] Pu(V) [22541-69-1] and Pu(VI) [22541-41-9] in mineral acids, ie, HCIO and HNO, have been measured (78—81). The Pu(VII) [39611-88-61] spectmm, which can be measured only in strong alkaU hydroxide solution, also has been reported (82). As for rare-earth ion spectra, the spectra of plutonium ions exhibit sharp lines, but have larger extinction coefficients than those of most lanthanide ions (see Lanthanides). The visible spectra in dilute acid solution are shown in Figure 4 and the spectmm of Pu(VII) in base is shown in Figure 5. The spectra of ions of plutonium have been interpreted in relation to all of the ions of the bf elements (83). 

Provitamin D. The molecular extinction coefficient of 7-dehydrocholesterol at 282 nm is 11,300 and is used as a measure of 7-dehydro isomer... 

Ellipsometry is a method of measuring the film thickness, refractive index, and extinction coefficient of single films, layer stacks, and substrate materials with very high sensitivity. Rough surfaces, interfaces, material gradients and mixtures of different materials can be analyzed. 

The refractive index of a film or a substrate material can be measured with a sensitivity better than 5 x 10, the best available for non-invasive optical measurement methods, especially for thin films. The extinction coefficient can be measured with almost the same sensitivity, which corresponds to a lower limit of 10-100 cm for the absorption coefficient of the material. 

Infrared ellipsometry is typically performed in the mid-infrared range of 400 to 5000 cm , but also in the near- and far-infrared. The resonances of molecular vibrations or phonons in the solid state generate typical features in the tanT and A spectra in the form of relative minima or maxima and dispersion-like structures. For the isotropic bulk calculation of optical constants - refractive index n and extinction coefficient k - is straightforward. For all other applications (thin films and anisotropic materials) iteration procedures are used. In ellipsometry only angles are measured. The results are also absolute values, obtained without the use of a standard. 

The solvent used was 5 %v/v ethyl acetate in n-hexane at a flow rate of 0.5 ml/min. Each solute was dissolved in the mobile phase at a concentration appropriate to its extinction coefficient. Each determination was carried out in triplicate and, if any individual measurement differed by more than 3% from either or both replicates, then further replicate samples were injected. All peaks were symmetrical (i.e., the asymmetry ratio was less than 1.1). The efficiency of each solute peak was taken as four times the square of the ratio of the retention time in seconds to the peak width in seconds measured at 0.6065 of the peak height. The diffusivities obtained for 69 different solutes are included with other physical and chromatographic properties in table 1. The diffusivity values are included here as they can be useful in many theoretical studies and there is a dearth of such data available in the literature (particularly for the type of solutes and solvents commonly used in LC separations). 

Extinction Coefficient a measure of the ability of particles or gases to absorb and scatter photons from a beam of light a number that is proportional to the number of photons removed from the sight path per unit length. See absorption. Extinction Cross Section the amount of light scattered and absorbed by a particle divided by its physical cross section. 

Reconstructed Extinction extinction estimate that results from summing up the product of the mass of each measured particle species and the appropriate absorption or extinction coefficient. 

For methane-air fireballs, Hardee et al. (1978) found an of 469 kW/m. If an extinction coefficient of k = 0.18 m (as measured in LNG fires) is used, the curve shown in Figure 6.8 can be obtained from the equations given by Hardee et al. (1978). Equation (6.2.3) overstates emissivity as determined through experiments. Possible explanations are... 

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