Absorption coefficient, spectral

The tinctorial strength in white reductions is thus quantitatively defined by the Kubelka-Munk relation between the spectral absorption coefficient K and the spectral scattering coefficient S in which [ refers to the reflection of a completely opaque layer. The ratio K/S is proportional to the tinctorial strength. 

Figure 24.3 Typical single-sweep measurements of spectral absorption coefficients kv, cm ) obtained by simuftaneousiy tuning two independent diode fasers at 10-kifohertz rates across H2O transitions near 1343 run (a) and 1392 nm (6). The measurements were made over a 5-centimeter path through the combustion region of a 5-kifowatt forced combustor operating on C2H4-air...

Figure 24.3 shows typical single-sweep (raw data) measurements of spectral absorption coefficients obtained simultaneously by tuning two diode lasers independently at 10-kilohertz rates across H2O transitions near 1343 and 1392 nm over a 5-centimeter path through the combustion region x/d = 2) of the forced combustor (jet diameter d = 2.1 cm, 4> = 0.75). The product of the spectral absorption coefficient at frequency v ki, cm ) and path length L, cm) is given by ki,L = ln(/o//)j/, where / and Iq are the transmitted and... 

Note that the spectral absorptivity, transmissivity, and emissivity of a medium are dimensionless quantities, with values less than or equal to l.The spectral absorption coefficient of a medium (and tlrus Ca, cta, and Ta), in general, vary with wavelength, temperature, pressure, and composition. 

FIG. 53. Spectral absorption coefficients of sheet glass at various temperatures and spectral distribution of black body radiation intensity in terms of temperature (after Neuroth, 1952 from Garden, 1968),... 

Table 5.7 Spectral absorption coefficient k of water according to [5.27]...

The spectral pure transmissivity decreases exponentially with the thickness of the body. An opaque body of thickness s has such a large spectral absorption coefficient that the product k(X)s reaches values over 7, then t 0 and a,[ ss 1. 

A homogeneous gas mixture has constant intensive properties T, p and pG over its entire volume. Its spectral absorption coefficient kG is, therefore, independent of s. So, from (5.177), the optical thickness is found to be... 

As the absorption of radiation takes place on the individual molecules of the gas, the assumption is suggested, that the spectral absorption coefficient kq is proportional to the molar concentration cq = Nq/V of the absorbing molecules or to the partial pressure pG = RmTcG. The optical thickness of a homogeneous gas is then given by... 

The spectral absorption coefficient /cq is also decisive for the radiation energy emitted by a volume element of the gas. d2 A,v indicates the radiation flow emitted by a volume element dV of a homogeneous gas in the wavelength interval dA into all directions. It holds for this that... 

Rimington C. Spectral absorption coefficients of some porphyrins in the Soret-band region. Biochem J 1960 75 620-3. 

In Chapter 3 Napierian units were used for absorption coefficients and absorbance. The reason was a simpler handling of the equations. Since instrumentation reads decadic units, they are used in most equations in this chapter. The decadic molar spectral absorption coefficient e of the compounds (i) varies with wavelength A. For this reason Bouguer-Lambert-Beer s law is restricted to monochromatic radiation. This restriction and the interactions between molecules in concentrated solutions cause two problems in applying the law to quantitative evaluation ... 

Determination of Spectral Absorption Coefficients and Calibration Curves... 

When evaluating the results, the calculation of the spectral absorption coefficient is rounded to 0.1 m". The result should be accompanied by a statement as to whether the water sample was filtered and at what wavelength the measurement was carried out. 

If sufficient numbers of measured values are available for other overall parameters for dissolved materials, an attempt can be made to establish a correlation. If this is successful, the control measurement can be restricted to determining the spectral absorption coefficient at 254 nm. 

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