Total scattering

In a dilute gas with molecules significantly smaller than the wavelength of light, the individual molecules act as point scatterers. For a gas consisting of N molecules in a volume of V m, the total scattering is A/V times the scattering from a single molecule. 

Direct calibration to absolute intensity is not a usual procedure at synchrotron beamlines. Nevertheless, the technical possibilities for realization are improving. Therefore the basic result for the total scattering intensity measured in normal transmission geometry is presented. At a synchrotron beamline point-focus can be realized in good approximation and the intensity /(s) is measured. Then integration of Eq. (7.19) results in... 

The best-known projection in the field of scattering is the scattering power k it is a number, k is the total scattered intensity63... 

The total scattering function, (s7,)/7o, may thus be derived from m For values of n encountered here, from 0 to 1.5, the graph of the absorption function n resembles that of the total scattering function,... 

As the salt concentration continues to decrease, however, matters change dramatically Q). The total scattering intensity decreases more abruptly, and the QLS autocorrelation function, which has been a simple single-exponential decay, becomes markedly two-exponential. The two decay rates differ by as much as two orders of magnitude. The faster continues the upward trend of D pp from higher salt, and is thus assigned the term "ordinary . The slower, which is about 1/10 of Dapp high salt, and appears to reflect a new mode of solution dynamics, is termed "extraordinary . 

The incoherent scattering is given by the difference between the total scattering and the coherent scattering. For a monatomic crystal with one atom per unit cell,... 

The anomalous components of the total scattering are wavelength dependent and the use of radiation close to an absorption edge may increase or optimise the contribution due to the anomalously scattering atoms. Ramaseshan (1962) pointed out that data collected at multiple wavelengths optimising the anomalous dispersion effects would improve the quality of phase determination. 

Fig. 4 The atomic form factor of a C atom (in ls 2s 2p electronic configuration). Core electron scattering is in blue. Valence electron scattering is in red and total scattering in black...

Figure 17 Total scattering cross section Cp (left axis) and rate (right axis) for the production of CO by electron impact on a 5-ML film of methanol condensed on an Ar spacer as a function of the incident electron energy. The dashed line is the intrinsic minimum rate of CO production due to the measurement at i = 14 eV. (From Ref. 37.)...

Demerjian et al., 1980). Also shown are these researchers estimates of total scattering plus absorption due to particulate matter, known as the aerosol extinction ... 

Figure 1.4 The total scattered field at P is the resultant of all the wavelets scattered by the regions into which the particle is subdivided. 

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