Extinction coefficient, molar Absorptivity

Molar absorptivity e = Ajbc Molar absorbancy index, molar extinction coefficient, molar absorption coefficient... 

Optical extinction coefficient = molar decaidic absorption. 

The decrease of molar extinction coefficients of absorption bands in the polarized spectra of piemontites with increasing Mn3+ ion contents ( 4.4.2), which is contrary to the Beer-Lambert law, eq. (3.7), indicates that Mn3+ ions are not located entirely in one site of the epidote structure ( 4.4.2.1). Most of the man-... 

From the above discussion, it is clear that for a photochemical process to occur, incident photons must be absorbed first. The more effective the absorption of light in a given spectral region (i.e., the higher the absorption cross-section for the excitation light), the more efficient the photoreaction is. This is measured by the molar extinction coefficient or absorptivity, Ex normally expressed in L mol-1 cm-1. The number of molecules photolyzed per photon of incident light in a fixed period of time is called the quantum yield for photolysis, . 

Sea salt aerosol particles form a unique chemical enviroiunent, exposed to much higher sunlight photon fluxes than found in the surface waters of the ocean and potentially the site of intense photochemical activity. Species that may interact with sunlight in marine aerosol particles are outhned in Table 2, which hsts known constituents and concentration ranges based on and inferred from previous studies. Obviously, these species and levels will vary significantly from study to study, but this merely serves to summarize the most important chromophores commonly found in marine aerosol particles. Based on estimated levels and absorbance cross-sections, specifically molar extinction coefficients and absorptivities, DOM will be the most dominant chromophore in sea salt aerosol particles (as it is in the surface ocean). The photochemical reactions that may occur in the marine aerosol are discussed in more detail in the following section. 

Note that the presence of the three protein forms can be qualitatively seen in the absorption sjjectrum (Fig. 5). However, as is described in (Banishev et al., 2009), the quantitative determination of the individual photophysical p>aratneters of their chromophore with the help of only conventional methods are ptroblematic. This is explained by the fact that the preparative separation of the forms is rather difficult and, as a result, it is hard to find their jjartial concentrations. At that rate, for example, for calculating the molar extinction coefficient (or absorption cross section) of chromophore from absorption spectra, the total protein concentration (total concentration of all forms) is used. As a result, the extinction coefficients are artificially underestimated (Kredel at al., 2008). At present, the only method that used for deterniining the individual extinction coefficient of chromophore of each sjjectral form can be found in (Ward, 2005). However, as it was pointed out in (Kredel et al., 2008), the values measured by the method are inaccurate in case of red FPs. Although, the procedure which enables to reduce the experimental errors has been proposed by (Kredel et al., 2008), the problem remains still topical. 

The fluorescent emission must be intense (fluorescence intensity is directly proportional to the product of the molar extinction coefficient for absorption and the quantum yield for the fluorescence emission of the dye). 

An important thing to note is that the intra-4/electronic transitions are parity forbidden and should thus not be observed. However, the formal selection mles are relaxed by spin-orbit coupling, which is significant because the lanthanides have high atomic numbers. Another way of saying that the selection mles are relaxed is that they steal intensity from allowed transitions (e.g. the ground state 4/ to 5d transitions). This forbidden nature of the intra-4/electronic transitions has two major consequences. One is the low molar extinction coefficient (or absorption cross section) with the %/2 transition of Yb " being one... 

The quantity e is called the absorption coefficient or extinction coefficient, more completely the molar decadic absorption coefficient it is a characteristic of the substance and the wavelength and to a lesser extent the solvent and temperature. It is coimnon to take path length in centimetres and concentration in moles per... 

Molar absorptivity used to be called the molar extinction coefficient... 

This is the fundamental equation of colorimetry and spectrophotometry, and is often spoken of as the Beer-Lambert Law. The value of a will clearly depend upon the method of expression of the concentration. If c is expressed in mole h 1 and / in centimetres then a is given the symbol and is called the molar absorption coefficient or molar absorptivity (formerly the molar extinction coefficient). 

Mohr procedure exptl. details of, 349, 351 Molar absorption coefficient 649 Molar conductivity 520 Molar extinction coefficient see Molar absorption coefficient Molar solution definition, 260 Molarity 259 Mole 259... 

The reduced symmetry of the chromophore, which still contains 187t-electrons and is therefore an aromatic system, influences the electronic spectrum which shows a bathochromic shift and a higher molar extinction coefficient of the long-wavelength absorption bands compared to the porphyrin, so that the photophysical properties of the chlorins resulting from this structural alteration render them naturally suitable as pigments for photosynthesis and also make them of interest in medical applications, e.g. photodynamic tumor therapy (PDT).2... 

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