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Publisher Summary Light scattering has developed into a powerful approach for measurements in fluid. This scattering arises when a beam of light, passing through a medium, interacts with it and consequently part of the beam is diverted or scattered. A fraction of this diverted light can be collected and analyzed to determine thermodynamic fluid properties from the intensity and its spectral distribution. The signals obtained from many different types of relatively simple molecules are spectrally separated. These separations are usually sufficiently large to allow non-interfering quantitative measurements so that concentrations can be independently obtained. Density information from vibrational Raman scattering data is very largely independent of temperature below the temperatures where substantial vibrational excitation occurs. It is found that as temperature increases, the vibrational band broadens, because higher rotational and vibrational levels are populated significantly, and thus, more individual rotational–vibrational lines begin contributing significantly to its shape. It is observed that rotational Raman scattering can be used advantageously to measure density of pure gases; in some experimental configurations, this can be accomplished with high sensitivity. |
