Particle absorption coefficient

Flere C is the volume concentration of j-phase particles is the mass concentration of the analyte in the j-phase particles w is the x-ray fluorescence radiation yield t. is the mass absorption coefficient of the analyte for the primar y radiation d. is the j-phase particle effective size r fs... 

The penetration of ions from the subphase into the shell of spread particles is a general phenomenon and can be used to modify and functionalize the particle surface. For example, metal ions, such as Ba and Fe, or cationic polyelectrolytes, such as the polycation of polyallylamine, can be adsorbed at anionic particles, while anionic water-soluble dyes, such as phthalocyanine tetrasulfonic acid and 1.4-diketo-3.6-diphenylpyrrolo[3.4-c]pyrrole-4, 4 -disulfonic acid (DPPS) [157], can be adsorbed at cationic particles. However, since only a monolayer of the dye is adsorbed, a deep coloration of the particles is not obtained unless a dye with very high absorption coefficient is used [156],... 

The metal formed is deposited on the colloidal particles and causes the absorption of the solution to increase at all wavelengtlK. The depositel cadmium is very reactive. It is reoxidized when air is admitted to the illuminated solution. Addition of methyl viologen to the illuminated solution under the exclusion of air yields the blue colour of the semi-ceduced methyl viologen, MV". As the absorption coefficient of MV" is known, the concentration of reduced cadmium can be readily calculated. reoxidises cadmium atoms ... 

The reaction of the trapped holes with Br ions adsorbed at the colloidal particles was used to determine the absorption coefficient of the holes. In the presence of Br less absorption of the holes is observed after the flash, as the Br ions react with some of the holes during the laser flash. On the other hand, the absorption of Br, i.e. the oxidation product of Br , can be seen. By comparing the decrease in h absorption after the flash with the absorption of Br, , and knowing the absorption coefficient of Br, the absorption coefficient of the hole, = 9.2 x 10 cm , was cal-... 

If total internal reflection does occur at point C, the amount of absorption could be doubled. Too long a path within the particle, or a very high absorption coefficient, could mean that all the light is absorbed and the colouring power of the particle will thus be lost. This demonstrates one reason why the mean particle size of the coloured pigment must be arranged to minimise this possibility. 

First item in a series (for example, the first carbon linked to a carboxyl group). 2. Abbreviation for alpha particle. 3. Symbol for angle of optical rotation. 4. Symbol for degree of dissociation. 5. Symbol for electric polarizability of a molecule. 6. Often with a subscript number (i) the coefficient of [A] in the numerator of the generalized rate expression. 7. Symbol for is proportional to. 8. Symbol for Napierian absorption coefficient. 9. In brackets, symbol for specific optical rotation. 

One must first link the source tb concentrations of each chemical species in the aerosol. Second, the contribution of each chemical species to the particle scattering and absorption coefficients must be determined. 

To test the applicability of statistical techniques for determination of the species contributions to the scattering coefficient, a one-year study was conducted in 1979 at China Lake, California. Filter samples of aerosol particles smaller than 2 ym aerodynamic diameter were analyzed for total fine mass, major chemical species, and the time average particle absorption coefficient, bg. At the same time and location, bgp was measured with a sensitive nephelometer. A total of 61 samples were analyzed. Multiple regression analysis was applied to the average particle scattering coefficient and mass concentrations for each filter sample to estimate aj and each species contribution to light scattering, bgn-j. Supplementary measurements of the chemical-size distribution were used for theoretical estimates of each b pj as a test of the effectiveness of the statistical approach. 

As a first cut, univariate regression was used to see relationships between pairs of measured variables. The results are summarized in Table 6. It is seen that the particle scattering coefficient is highly correlated with the total fine aerosol mass concentrations, sulfate, and ammonium. To a lesser degree it is correlated with the particle absorption coefficient, potassium, and the unaccounted mass concentration. My. The correlations between the particle scattering coefficient and the nitrate, total carbon (Ct) and crustal species are poor. The poor correlation, r=0.6J, between bgp and the soot concentration is probably an indication of the error in the soot measurement. Although the sulfate and the unaccounted mass are highly correlated with the total mass, they are not well correlated with each other (r=0.49). 

The parameter p,/p is a constant known as the mass absorption coefficient with the assumption that this is independent of the type of absorbing particles (an assumption that generally holds well enough to cause < 10% uncertainty), the value of In(/ //) is directly related to the parameter of interest, pX = mass per unit area. 

The exact absorption threshold of the absorption spectra was determined from the intercept of (crhv)2 versus hv plots (where absorption coefficient) for the direct band gap and was found to be 2.82-2.86 eV regardless of size. From a relationship between Eg and particle size of Agl after Meisel et al. (36), we found that the size of these particles was 6-7 nm. For the smallest particles, sample I, there is no peak in the spectra. Other than this finding, there is no apparent quantum confinement effect such as peak shift in the sample whose sizes are larger than 5 nm. 

Volume-normalized extinction is plotted in Fig. 11.2 as a function of photon energy for several polydispersions of MgO spheres both scales are logarithmic. For comparison of bulk and small-particle properties the bulk absorption coefficient a = Airk/X is included. Some single-particle features, such as ripple structure, are effaced by the distribution of radii. The information contained in these curves is not assimilated at a glance they require careful study. 

Fischer, K., 1973. Ma s absorption coefficient of natural aerosol particles in the 0.4-2.4 /am wavelength interval, Beitr. Phys. Atmos., 46, 89-100. 

Measurement of non-linear optical properties [580] also provides a means for characterizing size-quantized semiconductor particles. Third-order optical non-linearity of size-quantized semiconductor particles has been discussed in terms of resonant and non-resonant contributions [11]. Resonant non-linearity is expected to increase with decreasing particle size and increasing absorption coefficients. 

The theory of multiple scattering (scattering interaction) relates the scattering coefficient S to the pigment volume concentration o and to the scattering diameter Qs of the individual particle. The absorption coefficient K is directly proportional to the absorption diameter gA and the concentration a. 

The light absorption coefficient of black pigments determines their optical quality. Their color intensity and hiding power depend on the particle size and particle size distribution. The most important black pigments are carbon blacks, iron oxides (Section 3.1.1), and mixed metal oxides (Section 3.1.3). 

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