Absorption coefficients table

The effective absorption coefficient, eff, and threshold fluence, Fth, were calculated according to Eq. 1 and are summarized in Table 1. The aeff values calculated at low fluences are much larger than those obtained at high flu-ences. The effective absorption coefficients do not correlate with the linear absorption coefficients (Table 1), maybe with the exception of PI. A difference between the values of aeff and aan is observed for most polymers. An important feature is the similarity of aeff for all designed polymers, including PE (%54,000 5000 cm1), while PI reveals a much higher value (Table 1). 

The use of mass absorption (attenuation) coefficients has been discussed throughout this text, especially with regard to the calculation of primary and secondary absorption, interelement correction coefficients, and the fimdamental parameters method of quantitative analysis. Unfortunately, at this time no single, convenient, authoritative table of mass absorption coefficients is available. Variations between the data given in published mass absorption coefficient tables may be large and often depend upon the source and manner of obtaining and refining the data (either experimental or mathematical). Table A2.1 illustrates some variations of mass absorption coefficients as a function of the data source, and this is typical of most of the published data. 

In this section, commercially purchased carotenoid standards are dissolved in a suitable solvent and the absorbance measured at its maximum wavelength ( ax)- Using published absorption coefficients (Table 111.2) and taking into consideration the dilution factor, the concentration of the standard carotenoid is calculated. The spectrum is also scanned in order to evaluate the fine structure. 

With the exception of individual food colorants and single carotenoid pharmaceutical products, it is unlikely that the extract will be composed of only one predominant carotenoid therefore, a specific k ,ax or absorption coefficient (Table 111.3) cannot be used. In this case it is convenient to use a of 450 mn and a typical A value of 2,500. Alternative values and other considerations are discussed below. 

Table 7.8 Mass Absorption Coefficients for Ka., Lines and WLa-, Line...

Table 7.8 contains values of p,/p for the common target elements employed in X-ray work. A more extensive set of mass absorption coefficients for K, L, and M emission lines within the wavelength range from 0.7 to 12 A is contained in Heinrich s paper in T. D. McKinley, K. F. J. Heinrich, and D. B. Wittry (eds.). The Electron Microprobe, Wiley, New York, 1966, pp. 351-377. This article should be consulted to ascertain the probable accuracy of the values and for a compilation of coefficients and exponents employed in the computations. 

TABLE 7.8 Mass Absorption Coefficients for Kai Lines and W Lai Line (Continued)... 

AH materials, even those considered to be sound-reflecting, absorb some small fraction of the sound energy impinging on them. Table 1 provides sound-absorption coefficients for some common building materials. 

Table 1. Sound-Absorption Coefficients (a) for Some Common Building Materials...

Products. There is a large number of commercially available sound-absorbing products for use on ceilings, walls, and for other special appbcations. Sound absorption coefficients and NRC values for some sound-absorbing products and treatments ate indicated in Table 2. 

Only slightly less accurate ( 0.3—0.5%) and more versatile in scale are other titration techniques. Plutonium maybe oxidized in aqueous solution to PuO " 2 using AgO, and then reduced to Pu" " by a known excess of Fe", which is back-titrated with Ce" ". Pu" " may be titrated complexometricaHy with EDTA and a colorimetric indicator such as Arsenazo(I), even in the presence of a large excess of UO " 2- Solution spectrophotometry (Figs. 4 and 5) can be utilized if the plutonium oxidation state is known or controlled. The spectrophotometric method is very sensitive if a colored complex such as Arsenazo(III) is used. Analytically usehil absorption maxima and molar absorption coefficients ( s) are given in Table 10. Laser photoacoustic spectroscopy has been developed for both elemental analysis and speciation (oxidation state) at concentrations of lO " — 10 M (118). Chemical extraction can also be used to enhance this technique. 

TABLE 23-7 Selected Absorption Coefficients for CO in Various Solvents in Towers Packed with Raschig Rings ... 

For the three oclyloxy-subslitulcd five-ring oligomers, the normalized photoluminescence spectra of the single crystals are depicted in Figure 16-26. Due to the large absorption coefficient (more than 105 cm"1 at the maximum) we were not able to measure the absorption spectra of the relatively thick (20-30 pm) single crystals (see Table 16-5 in Section 16.3.3.3.1). 

The values of r and a in Table 4-2 show that photoelectric absorption generally makes the greater contribution to the mass absorption coefficient. Absorption leading to scattering, which will be discussed in the next section, gains in relative importance as atomic number Z and wavelength X decrease. 

Effective wavelengths have been included in Table 3-1 to show the changes that occur in this important variable when one gas is substituted for another. These wavelengths correspond to mass absorption coefficients calculated from Equation 3-14 and were obtained by interpolation from tabulated values of absorption coefficients for different wavelengths.15... 

The alternating component of the applied voltage causes a continuous variation in the efficiency of the x-ray excitation (Step II) during each cycle of operation. A polychromatic x-ray beam has a different total absorption coefficient and a different ratio of photoelectric to scattering absorption coefficient for each wavelength (Step V). It is very difficult to take account of these factors exactly. Fortunately, reasonable estimates will suffice in the making of the calculations for Table 4-4 and Figure 4-15. The efficiency has been taken as that for the root-mean-... 

The concordance of the results in Figure 6-2 with the known mass absorption coefficients of iron may be judged from Table 6-1. 

Inspection of the table shows that the quotient a/Wj e is in fact nearly constant that I changes much less rapidly than W e] and that the critical depth has doubled when the highest oxide is reached. All three conditions are reflections of the (positive) absorption effect that occurs in this binary system when iron is replaced by oxygen, which has a lower mass absorption coefficient. 

Table 3.3 Mass fractions and mass absorption coefficients for Ci6ioH3624NnoFePioiF606...

Table B.l Mass absorption coefficients for the 14.41-keV Mossbauer radiation of Fe...

Meyer-Dulheuer [55] has analysed the pure additives (phenolic antioxidants, benzotriazole UV stabilisers and HALS compounds) of Table 9.8 in THF solutions by means of MALDI-ToFMS. As it turns out, polar molecules in the mass range of below 800 Da, which have a high absorption coefficient at the laser wavelength used, can often be measured without any matrix [55,56]. In this case, there is no matrix-assisted laser desorption and ionisation (MALDI) process any more. It is a simple laser desorption/ionisation (LDI) process. The advantage of this method is a matrix-free mass spectrum with the same mass resolution as in the MALDI case,... 

When the concentration of chloride ion was below 3 M, further aquation reactions from Tc(H20)ClJ to Tc(H20)2C14, etc. were observed. Similarly, aquation of hexabromotechnetate(IV) was studied (molar absorption coefficient, s445 nm = 5720 M "1 cm "1). The equilibrium constants K for Eq. (9) at different temperatures are summarized in Table 2. Analysis of the aquation rate gave the following equation ... 

The photoelectric mass absorption coefficients of these polymegs and of poly(methyl methacrylate) PMMA at 8.3 X and 13.3 + A are shown in Table II. These coefficients were calculated using relation (8) and the data listed in Table I. 

Table I. Photoelectric Mass Absorption Coefficients of Halogen Atoms and of Carbon, Oxygen, Hydrogen at 8.34 A (A1 Kali2 emission line) and 13.34 A (Cu Lai. o emission line) (6)...

Table II. Photoelectric Mass Absorption Coefficients of the Halogenated Polymethacrylates and of PMMA...

Example PET. Let us consider polyethylene terephthalate) (PET, C oHK(h n, Ppet=1-35 g/cm3) of tpET =2 mm thickness and an X-radiation wavelength X= 0.15418 nm (CuKa). We set up a table with one row for each chemical element and sum both the masses and the mass absorption coefficients multiplied by the masses. After normalization to the molecular mass of the PET monomer, 192.17 amu, we find (p/p)pet = 1291.97/192.17 cm2/g a value 6.72 cm2/g. Considering the density ppet we find for the linear absorption coefficient Ppet =... 

The pulse radiolysis technique gives a direct way for measuring the hydrated electron yield. To get the stationary yield, one can simply follow the electron absorption signal as a function of time and, from the known value of the extinction coefficient (Table 6.2), evaluate g(eh). Alternatively, the electron can be converted into a stable anion with a known extinction coefficient. An example of such an ion is the nitroform anion produced by reaction of eh with tetrani-tromethane (TNM) in aqueous solution ... 

TABLE 1. Observed absorption maxima (Amax) and molar absorption coefficients (g) of unsubstituted all-trans-polyenes... 

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