Spectral radiant

Spectral radiant energy den- Surface charge density (J... 

Spectral radiant energy flux d(j)/dk Surface pressure 7T... 

Ratio Pyrometers The ratio pyrometer is also called the two-color pyrometer. Two different wavelengths are utilized for detecting the radiated signal. If one uses Wien s law for small values of XT, the detected signals from spectral radiant energy flux emitted at the wavelengths and 2 with emissivities and are... 

The term intensity is commonly used but is imprecise. According to IUPAC recommendations (see Pure 6[ Appl. Chem. 68, 2223-2286 (1996)), this term should be replaced by the spectral radiant power Ph i.e. the radiant power at wavelength X per unit wavelength... 

The emitted spectral radiant power (or exitance) or the emitted spectral photon trradiance (or exitance) plotted as a function of the frequency, wavenumber, or wavelength. The corrected emission spectrum has been cor-... 

Fig. I. Spectral radiant cxciiance of a blackbody at various temperatures...

Figure 8.3 Spectral radiant power (per unit time per unit area) distribution of a blackbody at various temperatures. Note that the maximum intensity, even at 3500 K, is still in the infrared region of the spectrum. The displacement of the maximum of the radiant energy shifts linearly with absolute temperature (dotted lines) in accordance with Wein s displacement law.

Quantitatively, absorption is often expressed as absorbance (A), which is the logarithm to the base 10 of the ratio of the spectral radiant power of incident, essentially monochromatic (of A wavelength), radiation (P°) to the radiant power of transmitted radiation (P.y. 

Spectral quantities may also be defined with respect to frequency v, or wavelength 2 see spectral radiant energy density above. 

The Planck theory of blackbody radiation provides a first approximation to the spectral distribution, or intensity as a function of wavelength, for the sun. The black-body theory is based upon a "perfect" radiator with a uniform composition, and states that the spectral distribution of energy is a strong function of wavelength and is pro portional to the temperature (in units of absolute temperature, or Kelvin), and several fundamental constants. Spectral radiant exitance (radiant flux per unit area) is de fined as ... 

Example 3-6 a) Calculate the photon flow Op in mol h- at X = 253.7 nm of a low-pressure mercury lamp (type NN 50/81, Heraeus) that has an electric input power Pel of 50 W and a radiant power efficiency ri = Px/P x 100 = 40% at this wavelength Px- spectral radiant power in W nm- ) b) compare this value with Op at X = 253.7 nm of a medium-pressure mercury lamp with a spectral radiant power 253.7 nm of 1.035 kW (refers to a 20 kW lamp). 

Aio is the (decadic) absorbance of a beam of collimated monochromatic radiation in a homogeneous isotropic medium (Verhoeven, 1996) is the incident spectral radiant power ... 

The transmittance T is the ratio of transmitted spectral radiant power to... 

Especially, for AOPs it is essential to note that the absorbance A is an additive property (cf. Braun et al, 1991), with the consequence that the individual compounds of a wastewater or a gas mixture may compete for the absorption of the incident spectral radiant power. Hence, the concentrations C of any radiation absorbing species i present in water or air must be considered as well as their individual molar absorption coefficients Therefore, the Beer-Lambert law changes to Eq. 3-8, which describes the absorbance A of a multi-component mixture at a specified wavelength X. 

According to Pfoertner (1998) the absorbed spectral radiant power P f of a specific component i is related to the spectral radiant power P absorbed by all other components of a mixture according to the relationships of Eqs. 3-9 and 3-10. 

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