Intensity fluctuations in forward scattering and temporal coherence.
The problem of forward scattering by a nonergodic system of identical particles is considered. The analysis of statistical characteristics of intensity fluctuations arising as a result of finite observation time shows that the mean dispersion of intensity fluctuations can be expressed as a function of the wavelength, diffusion coefficient, scattering angle, and observation time. The relation between the temporal correlation function of the scattered radiation and its second-order intensity moments is established. Quantitative estimates of the effect with the infrared laser beam propagating through fog give results comparable to the dispersion due to refractive index fluctuations in a pure atmosphere (Tatarskii).
Scattering and Attenuation due to Snow at Optical Wave-lengths
THE narrow beam-widths obtainable with coherent light permit one to examine forward scattering caused by atmospheric effects in some detail. For example, it is found that inhomogeneities of refractive index in the otherwise clear atmosphere give rise to considerable broadening of a narrow beam. However, when heavy snow is falling, scattering and the ensuing attenuation of the optical wave are caused predominantly by the flakes; this also holds true in propagation through droplets of fog and rain.
Spin label motion in fatty acids.
Spin labels dissolved in highly purified fatty acid systems exhibit nearly identical tumbling rates in liquid and solid phases. Even though the spin labels do not have the same molecular geometry as the lipid matrix the melting point of the matrix can be inferred by measurements of the temperature dependency of molecular motion.