Scattering Intensity and Sample Structure

While the general relationship between the scattered intensity and the structure is so complicated that there is no general procedure applicable for the analysis of data from all kinds of samples, relatively simple methods can be used to interpret the scattering curves from the coals. 

Small-angle neutron scattering gave peaks which corresponded to crystalline CFj groups and to structures containing clustered ionic groups with assodated water molecules. The crystalline peaks disappeared in samples quenched from the melt. The number of water molecules per ionic group was deduced from the scattered intensity and rose from 1.7 in room-temperature-dried samples to 20 in boiled samples. 

The field of science that studies the interaction of electromagnetic radiation with matter is known as spectroscopy. Spectroscopic studies on the wavelength, the intensity of the radiation absorbed, emitted, or scattered by a sample, or how the intensity of the radiation changes as a function of its energy and wavelength, provide accurate tools for studying the composition and structure of many materials (Davies and Creaser 1991 Creaser and Davies 1988). 

Guinier s law exhibits two parameters, I (0) and R2, which describe structural aspects of the sample. The experimentalist should consider their determination, if the recorded SAXS data show a monotonous decay that is indicative for the scattering from uncorrelated1 particles. Particularly useful is the evaluation of Guinier s law, if almost identical particles like proteins or latices are studied in dilute solution (cf. Pilz in [101], Chap. 8). The absolute value of 1(0) is only accessible, if the scattering intensity is calibrated in absolute units (Sect. 7.10.2). 

Resonance Raman spectroscopy has been applied to studies of polyenes for the following reasons. The Raman spectrum of a sample can be obtained even at a dilute concentration by the enhancement of scattering intensity, when the excitation laser wavelength is within an electronic absorption band of the sample. Raman spectra can give information about the location of dipole forbidden transitions, vibronic activity and structures of electronically excited states. A brief summary of vibronic theory of resonance Raman scattering is described here. 

Scattering data over the extended range of q-space were also collected from Nafion samples containing a wide range of water contents = 0.05—0.84). While systematic shifts in the intensities and positions of the structure maxima (i.e., the crystalline and ionomer peaks) were observed and consistent with those found by others, the general shapes of the scattering profiles for all samples were quite similar. This observation supported the assumption that the swelling process simply involves a dilution of the... 

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