Absorbance cross section

From the data in Fig. 5 one can also deduce the vibrational temperature of photodetached CO. Assuming the absorbance cross section for the first hot band transition (2 1) is twice that for the ground state tran-... 

Conversion spectrum A plot of a quantity related to the absorption absorbance, cross section, etc.) multiplied by the quantum yield for the considered process against a suitable measure of photon energy, such as frequency, v, wavenumber, a, or wavelength, X. F.g., the conversion cross section, a , has the SI unit m. ... 

Multicolored luminescence is the most attractive property of rare earth-based compounds. Lanthanide ions possess many sharp emission lines that cover the visible and near infrared (NIR) region due fo fhe abundanf fransifions of f-orbital configurations. However, the forbidden f-f fransi-fions induce narrow excitation lines for mosf rare earfh ions. This low absorbency cross-section is the bottleneck in practical application, so host-sensitized emission mode is commonly employed by rare earth phosphors. The vanadate matrix is one of fhe candidafes, which excifes lanthanide ions via charge-transfer energy migration. 

It is sometimes useful to picture the extinction coefficient, , as the (hypothetical) cross-section area of the chromophore that is absorbing the light. The absorbance cross-section (o) is numerically related to e as follows ... 

A Consider a volume element in the solution of 1 cm cross-section area and length d/ (in cm). The number of molecules (chromo-phores) in this volume element will be 10 A aC X d/, where c is the chromophore concentration (in mol dm ). If each of these chromophores has an absorbance cross-section cr, then the fraction of light absorbed by this volume element is ... 

Q What is the absorbance cross-section, cr, at 280 nm for the tryptophan chromophore whose molar extinction coefficient is 280 = 5600 (mol dm ) cm How does this compare to the actual physical dimensions of this molecule ... 

In resonance Raman experiments it is very important to consider the effect of the absorbed light on the sample composition. Raman scattering and absorption are independent events. Some photons are scattered, but a much larger number are absorbed. Cross sections for Raman scattering are on the order of 10" A /molecule, whereas cross sections for absorption are about 1 A /molecule. Thus, if photon absorption results in a photochemical transformation, as in the case of visual pigments, the effect of the photoalteration must be carefully considered. This situation has been analyzed in detail and rapid-flow methods devised that allow one to obtain resonance Raman spectra of even the most photolabile molecules without distortion of the sample composition. " ... 

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. 

Herein a and a a are total and absorbing cross sections contained in unit volume. The above described experiments will be used to determine k for our U metal of density 8.6 to be... 

The maximum allowable velocity of the gas phase, referred to the free absorber cross section Wg an. depends on the flooding point or upper loading limit for the selected internals, for example, as calculated by the methods presented in Chapter 2. 

The infinite dilution limit can be obtained from either Equation (2.10) or Equation (2.14) by neglecting all absorber cross sections as compared with the moderator cross sections. The collision density is then given by the asymptotic form Equation (2.9), with = 0. Also, with at = one obtains from Equation (2.11) simply... 

Tb absorber cross section and dTg = scatterer cross section ... 

Glazer, A. N. Mathies, R. A. Hung, S. C. Jue, J. Cyanine dyes with high-absorbance cross section as donor chromophores in energy transfer labels. PCX Int. Appl. WO 9814612, 1998 Chem. Abstr. 1998, 128, 280583. 

The sensitivity of a reactor, which is defined as the change in the reproduction factor occurring when one square centimeter of absorber cross-sectional area is placed at a certain position in the reactor core, can be estimated by theoretical considerations. The use of the basic reactor diffusion equations to describe the change in k caused by small changes in reactor parameters is formulated in perturbation theory. Experimentally, the sensitivity of the reactor can be measured in terms of a standard absorber. Boron, whose absorption cross section has a l/v dependence, will be used for this measurement. Its cross section will be taken as the value at 2200 m/sec. The subsequent cross-section measurements of 1/v-absorbers by the danger coefficient method will yield their tive values at the same velocity. For an absorber which does not... 

---