Absorption linear

SubstiPitmg into equation (A 1.6.110) we find that the linear absorption spectrum is given by... 

The dynamic absorption signal, can be written in a fonn which looks analogous to the linear absorption signal (see equation (A1.6.113)). 

Both nonlinear and linear absorption can contribute to losses (3,53), ie. 

For extremely small penetrations a technique may be employed which depends upon the weak penetration of charged atoms with a known absorption law. The a-particles, which are He + ions, have a linear absorption... 

D, is the dose rate emerging from a shield of thiekness t u is the linear absorption eoeffieient of shield material. 

Now, in gas/liquid chromatography, very small concentrations of solute are employed and linear absorption isotherms are to be expected. However, in LC the detectors have much lower sensitivities and as a result, significantly larger charges... 

Figure 4-2. INDO/SCI-siuiulaled linear absorption spectrum of the eleven-ring PPV oligomer. The vertical lines represent the oscillator strength of the transitions that are described the site labeling used tor the wavcluiiclion analyses is shown on lop.

Figure 7-13. (a) Linear absorption of DOO-PPV, (b) imaginary part of ) (proportional to two-photon absorption), and (c) real part ol (proportional to the nonlinear index of refraction. .). 

Other absorption coefficients are also used, the most important of which is the linear absorption coefficient, ni, used in thickness measurements. In accordance with its definition, ni is given by the equation... 

In quantum theory as well as in classical theory, linear absorption of light at frequency co is described by a spectral function... 

Linear Absorption of Embedded Metal Clusters The Mie Theory... 

Linear absorption measurements can therefore give the first indication of possible alloy formation. Nevertheless, in systems containing transition metals (Pd-Ag, Co-Ni,. ..) such a simple technique is no longer effective as interband transitions completely mask the SPR peak, resulting in a structurless absorption, which hinders any unambiguous identification of the alloy. In such cases, one has to rely on structural techniques like TEM (selected-area electron diffraction, SAED and energy-dispersive X-ray spectroscopy, EDS) or EXAFS (extended X-ray absorption fine structure) to establish alloy formation. 

Absorption Coefficient—Fractional absorption of the energy of an unscattered beam of x- or gamma-radiation per unit thickness (linear absorption coefficient), per unit mass (mass absorption coefficient), or per atom (atomic absorption coefficient) of absorber, due to transfer of energy to the absorber. The total absorption coefficient is the sum of individual energy absorption processes (see Compton Effect, Photoelectric Effect, and Pair Production). 

Absorption Coefficient, Linear—A factor expressing the fraction of a beam of x- or gamma radiation absorbed in a unit thickness of material. In the expression I=I0e+l x, I0 is the initial intensity, I the intensity of the beam after passage through a thickness of the material x, and p is the linear absorption coefficient. 

Absorption Coefficient, Mass—The linear absorption coefficient per cm divided by the density of the absorber in grams per cubic centimeter. It is frequently expressed as p/p, where p is the linear absorption coefficient and p the absorber density. 

Thus, the fraction of dose absorbed is exponentially related to the absorption number. Equation (10) shows that the absorption number (and therefore the membrane permeability) is a fundamental parameter while other parameters such as the partition coefficient and pKa are useful guides but not fundamental parameters. For highly soluble drugs with linear absorption kinetics, dose and dissolution have no effect on the fraction of dose absorbed. In the case of drugs that are absorbed by a carrier-mediated process, a mean permeability should be used [30],... 

Before being able to study the nonlinear optical properties of any material, it is necessary to have a complete understanding of its linear optical properties. Therefore, we start this section with a brief discussion of the techniques used to measure some of the most important linear properties, e.g., linear absorption, fluorescence, anisotropy, and fluorescence quantum yield. 

In most cases, the linear absorption is measured with standard spectrometers, and the fluorescence properties are obtained with commercially available spectrofluo-rometers using reference samples with well-known <1>F for calibration of the fluorescence quantum yield. In the ultraviolet and visible range, there are many well-known fluorescence quantum yield standards. Anthracene in ethanol (Cresyl Violet in methanol (commonly used reference samples for wavelengths of 350-650 nm. For wavelengths longer than 650 nm, there is a lack of fluorescence references. Recently, a photochemically stable, D-ji-D polymethine molecule has been proposed as a fluorescence standard near 800 nm [57]. This molecule, PD 2631 (chemical structure shown in Fig. 5) in ethanol, has fluorescence spectra of the reference PD 2631 in ethanol to... 

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