Absorption constant

The refractive index of the sample can be written as a complex number 2 = n2 — ik2. At wavelengths where the sample is not absorbing, 2, the absorption constant, equals zero. However, kj is non-zero at wavelengths where the sample is absorbing. In transmission spectroscopy, the intensity of an absorption band depends almost entirely on k2 while in ATR the intensity of the same band is a complex function of 2 and 2- Nevertheless, the statement made previously still holds. There will be absorption bands in ATR at wavelengths where 2 0. Thus, bands are expected at the same wavelengths in transmission and in ATR but their intensities may be dissimilar. 

JOC420, 53CRV191), R is the gas constant, T is the temperature, and pa ( absorption constant ) is the slope of the line. According to this equation, the energy differences are a linear function of the and Gp... 

In fact, the absorptivity constant a is dependent upon the wavelength of the radiation as well as the nature of the absorbing material, whose concentration C is usually expressed in grams per litre. 

Thermodynamic equilibrium constant for over-all reaction Adsorption equilibrium constant for species /, or product of absorption constant and initial mole fraction of species i... 

Energy from a light beam is absorbed by molecules with a chromophore. An absorption spectrophotometer uses this mechanism, and the energy loss depends on the concentration and molecular absorption constant of analyte molecules and the wavelength of the light. The most popular detector, the... 

For ultraviolet and visible spectroscopic detectors, a standard solution of a compound whose molar absorption constant is known must be prepared, and placed in the flow cell. The absorbance obtained is then compared with the value measured by a standard spectrophotometer. 

The maximum absorbable dose (MAD) can be derived from the mixing tank model as shown by Johnson and Swindell [29], The amount of drug absorbed (Xa) at any time is a function of a first-order absorption constant (Ka) and the amount of dissolved drug (Xd) as described in Eq. 6. 

KINPTR Real-Time Activity Parameters for C6 System [Eqs. (50)—(52)] and Absorption Constants... 

A nonelectronic method of measuring impurity concentrations is that of absorption spectroscopy. From Eq. (36a) it is seen that ani = avnini0, where a i is the absorption constant due to electronic transitions from level i to the conduction band. The total impurity concentration Nt can be related to ni0 by a knowledge of EF. The photon-capture cross section doping experiments or by independently measuring Nt in some sample. This process has been carried out for Cr impurity (Martin, 1979) as well as (EL2) (Martin, 1981) in GaAs. The same considerations hold for photoconductivity measurements, except that t also needs to be known, as seen from Eq. (35). 

The optical constants—refractive indices, reflecting powers and absorption constants—of isolated crystals of tellurium placed in various positions relative to the plane of incidence have been determined 3 for wave-lengths of 3000 to 5000 A. The absorption of light by tellurium vapour reaches a maximum at 1200° C.4... 

The optical constants of vapor-deposited films of quinquethiophene (T5) are presented and compared to those of suspensions of colloidal T5 nanoparticles, which serve as model systems for the films [99MI395]. In nanoparticles, the maximum value of the absorption constant in the direction of the optical axis is kz = 1.8. It is reached at v 26,000 cm 1 and is due to the HOMO-LUMO-(S )-transition. The maximum of the absorption constant for the directions perpendicular to the optical axis, kXj y = 0.3, is found at v = 28,500 cm-1, and is probably due to the Sli2 transition. 

Absorption constant from gastrointestinal tract into liver (per hour) 0.02 0.02 0.2 — —... 

The ratio /spectrophotometric measurement, and the value of a is then calculated from eq. (3.5) to yield the desired absorption constant. The numerous absorption constants found in the literature arise from the choice of quantities incorporated in the constant b. Some of the terms most commonly used to express absorption in minerals are summarized in table 3.2. Note that optical densities (O.D.), representing the direct output from many spectrophotometers, lack specificity about sample thickness and element concentrations. Absorption coefficients (a) indicate that sample thicknesses have been measured or estimated. Molar extinction coefficients (e) require chemical analytical data as well as knowledge of sample thicknesses. 

We report the one-compartment probabilistic transfer model receiving the drug particles by an absorption process. In this model, the elimination rate h was fixed and the absorption constant hev was random. For the stochastic context, the difference hev — h = w is assumed to follow the gamma distribution, i.e., W Gam(A, //.) with density / (w, A, //.) and E [W] =... 

The quantitative relationship is expressed by the Beer—Lambert Law, A — abc, where A is absorbance, a the absorptivity constant, b the cell path length and c the sample concentration. More simply, it states that the amount of light that is absorbed by a sample is a function of the number of absorbing atoms in the light path. Clearly, the number of atoms is a function of the sample cell path length and the concentration of the sample. 

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