Spectrum of scattered light

Dynamic Light Scattering Dynamic light scattering is applied in a number of related methods wherein the spectrum of scattered light is determined by both static and dynamic means. The most valuable additional information obtained is the rotational divisional coefficient of the polymer. 

An alternative to the common device of determining relative intensities is a study of the fine structure of the scattered beam. This entails resolving the spectrum of scattered light into its three peaks, viz. a central peak and two side ones. The need is thus obviated to refer to I0 or, according to the apparatus, the scattering power of a standard calibration material. The method is used mainly for determining diffusion constants and thermodynamic properties of liquids. 

The spectrum of scattered light contains dynamical information related to translational and internal motions of polymer chains. In the self-beating mode, the intensity-intensity time correlation function can be expressed (ID) as... 

Since Raman was the first to publish a spectrum of scattered light containing frequency-shifted lines, he received the Nobel prize for physics on December 11, 1930, for his work on the diffusion of light and for the discovery of the effect which bears his name. ... 

By applying an electric field to a solution of macromolefl les, the molecules are accelerated to a terminal velocity determined by their electrophoretic mobilities.22 The spectrum of scattered light is thereby Doppler-shifted to a frequency determined by Eq. (5.8.15). From the Doppler shift the mobility can be measured, whereas from the width of the Doppler shifted line the diffusion coefficient can be measured [cf. Eq. (5.8.10)]. In this way Ware and Flygare (1971) have measured the electrophoretic... 

An clastic wave propagates with the velocity V, and Doppler s shift in frequency must occur. Of all possible directions of elastic waves, only two meet condition 17 those which propagate along two opposite directions with the velocities +V and - V, so the spectrum of scattered light is split into Mandelshtam-Drillouin s doublet (Fabelinski, 1965 Kerker, 1969 Vuks, 1977)... 

The spherically symmetric part of the diatom polarizability is related to the polarized spectrum of scattered light and to the second dielectric virial coefficient according to =... 

Fig. 7. Typical diagram of the spectrum of scattered light as measured by a Fabry Perot interferometer showing the Rayleigh line (center) and the Brillouin doublet. From the frequency shift and the width of the Brillouin bands one can obtain the storage and loss moduli fin- compresacHKil waves exxuring at hypersonic frequencies...

Thus each allowed Raman coupling generally produces two frequencies in the spectrum of scattered light, shifted to the negative and positive sides of the dominant Rayleigh line by the same amount, Av = AE/h, For this reason Raman spectroscopy is concerned with measurements of frequency shifts, rather than absolute frequencies. In most cases a number of Raman transitions can take place, involving various molecular energy levels, and the... 

If we want to calculate the full spectrum of scattered light then we find that the inclusion of these off-shell events prevents us from using the quantum fluctuation regression theory. To calculate spectra the dipole autocorrelation must be calculated directly without the use of any regression assumptions. This is an interesting example of where a microscopic calculation of a correlation function can be calculated for a system driven from thermal equilibrium. 

Each of the resonances appearing in the spectra are identified and characterized by the type (TE or TM), mode number n, and mode order 5 (i.e., TE J. Allowances were made in the fit for a small amount of scattered light polarized perpendicular to the scattering plane (due to imperfect alignment of the polarizer) and a small change in the particle radius due to evaporation during the experiment. Once the resonances are identified there are no adjustable parameters in the simulation of an excitation spectrum of a... 

For a 1 the scattered light spectrum is gaussian with a width determined by the electron temperature, because it is due to the incoherent sum of Thomson scattering from individual, thermally moving electrons. The intensity and spectral linewidth of scattered light therefore yield electron density and temperature. 

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