Scattering from single particle

Coherent quasi-elastic neutron scattering due to the pair-correlation of atomic motions is more complex than incoherent scattering from single particle motion. Therefore, the theory of coherent scattering function is not yet fully developed. However, approximate expressions for the coherent scattering function exist (incoherent approximation). 

Optical particle counters—single counter useful for only 1 decade of size requires calibration sensitive to shape and refractive index 0.3 (commercial) 0.1 (research) 3-100 >200 possible 20 useful 1 particle/L Light-scattering from single particles... 

Recently, a low-resolution model of the chromatin core particle has been derived from a combination of single-crystal X-ray diffraction and electron microscopic data (Finch et al., 1977). The particle is described as a flat cylinder 110 A in diameter and 57 A in height. A similar shape and similar dimensions were found to be consistent with the low-angle neutron scattering from core particles in solution (Pardon et al., 1977 Suau et al., 1977). Some conclusions may be drawn concerning the conformation of the DNA. Presumably, the strong 28 A periodicity apparent in the crystal data (Finch et al., 1977) corresponds to the pitch of the DNA superhelix wound about the histone core. X-Ray and spectroscopic data suggest that the DNA super-... 

The terms Q, Qabe, and Qext represent loss of radiation along the path from source to observer, i.e., the extinction of light by an aerosol. But often interest centers more on the scattering of light in a single direction. The diameter of a particle can be estimated by the quantity of light scattered from the particle into a detector. Or, if a thundercloud is to be tracked by radar, the intensity of radiation back-scattering is important. 

Fig. 9.3. Dark field light scattering spectra from single particles and pairs of particles illustrate plasmon coupling (see text) [11]...

For the optical particle counter of Fig. 6.5, the sensing volume is 1.5 x 1.5 x mm. Determine the total energy scattered by the air molecules in the volume. Compare this with the scattering by single particles with diameters ranging from 0.05 to 5 / m and a refractive index of 1.5. Assume k = 0.5 m and express your answers in terms of the incident intensity. The temperature is 20 0,... 

Emory and Nie described a particularly interesting approach the combination of near-field effects from tapered single-mode fiber probes with surface enhanced Raman scattering from single Ag colloidal nanoparticles [113]. By using the combined enhancement effects of molecular (rhodamine 6g) and particle... 

The distribution of intensity of scattered radiation in a diffraction pattern is related by a Fourier transformation to the autocorrelation function of scattering density, p r)p(r )), where ( ) indicates an average over the sample. In crystallography the autocorrelation function is known as the Patterson function. It is very useful to factor out contributions to the total intensity from interfering waves scattered by single particles and from interparticle interferences ... 

Total internal reflection microscopy (TIRM) was introduced in 1987 by Prieve et al. [343]. TIRM allows to probe the interaction of a single microsphere with a transparent flat plate. In a TIRM experiment, a microsphere is allowed to sediment toward the plate. The technique relies on repulsive forces between sphere and plate. This repulsion will typically result from electric double layer or steric forces. They keep the sphere from getting into contact with the plate. Thermal fluctuations will constantly change the precise distance. The distance between sphere and plate is monitored by the light intensity scattered from the particle when illuminated by an evanescent wave and can be determined with a resolution of w 1 nm. By recording the fluctuations in vertical position of the sphere due to Brownian motion, the potential energy of interaction and the diffusion coefficient of the sphere can be deduced. For overviews of the technique, see Refs [344, 345]. 

The biggest change associated with going from one to tliree dimensional translational motion refers to asymptotic boundary conditions. In tiiree dimensions, the initial scattering wavefiinction for a single particle... 

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