Raman light scattering

Previous findings on the actual microemulsion are given in references (9 17) where the system s phase map vs.concentration in the temperature interval (-20°C + 80°C), viscosity measurements,dielectric analysis of liquid samples against both concentration and frequency, the thermally stimulated dielectric polarization release (TSD), electro-optical phenomena, light scattering, Raman spectroscopy and sound propagation investigations are reported. 

Vibrational spectroscopy conventional IR spectroscopy with biological molecules in water is difficult, but this can be overcome by using laser inelastic light scattering (Raman) techniques. 

Raman spectroscopy is a technique for smdying molecular vibrations by light scattering. Raman spectroscopy complements IR absorption spectroscopy because some vibrations, as we have seen, do not result in absorptions in the IR region. A vibration is only seen in the IR spectmm if there is a change in the dipole moment during the vibration. For a vibration to be seen in the Raman spectmm, only a change in polarizability is necessary. 

Optical devices Changes in light intensity, color, or emission spectra Absorbance Reflectance Luminescence Refractive index Optothermal effect Light scattering (Raman scattering, plasmon resonance)... 

Ulness D J and Albrecht A C 1997 A theory of time resolved coherent Raman scattering with spectrally tailored noisy light J. Raman Spectrosc. 28 571-8... 

Spectroscopic examination of light scattered from a monochromatic probe beam reveals the expected Rayleigh, Mie, and/or Tyndall elastic scattering at unchanged frequency, and other weak frequencies arising from the Raman effect. Both types of scattering have appHcations to analysis. 

Raman Spectroscopy. Raman spectroscopy is an excellent method for the analysis of deuterium containing mixtures, particularly for any of the diatomic H—D—T molecules. For these, it is possible to predict absolute light scattering intensities for the rotational Raman lines. Hence, absolute analyses are possible, at least in principle. The scattering intensities for the diatomic hydrogen isotope species is comparable to that of dinitrogen, N2, and thus easily observed. 

There are still other surface analysis techniques including ellipsometry, surface enhanced Raman scattering, light scattering, nano-hardness measurements etc. which are used for specific investigations. It is, however, already evident from this discussion that many new and powerful techniques now are available which offer the capability of investigating various aspects of polymer surfaces on a molecular level. Some of those techniques are surface specific while others can be used for the analysis of buried interfaces, too. 

Cyvin, S. J., Rauch, J. E. and Decius, J. C. (1965) Theory of hyper-Raman effects (nonlinear inelastic light scattering) selection rules and depolarization ratios for the second-order polarizability. 

NMR IR/Raman EM ESR Fluorescence Neutron scattering X-ray Light scattering Calorimetry md ... 

Raman spectroscopy is an inelastic light scattering experiment for which the intensity depends on the amplitude of the polarizability variation associated with the molecular vibration under consideration. The polarizability variation is represented by a second-rank tensor, oiXyZ, the Raman tensor. Information about orientation arises because the intensity of the scattered light depends on the orientation of the Raman tensor with respect to the polarization directions of the electric fields of the incident and scattered light. Like IR spectroscopy, Raman... 

In these sensors, the intrinsic absorption of the analyte is measured directly. No indicator chemistry is involved. Thus, it is more a kind of remote spectroscopy, except that the instrument comes to the sample (rather than the sample to the instrument or cuvette). Numerous geometries have been designed for plain fiber chemical sensors, all kinds of spectroscopies (from IR to mid-IR and visible to the UV from Raman to light scatter, and from fluorescence and phosphorescence intensity to the respective decay times) have been exploited, and more sophisticated methods including evanescent wave spectroscopy and surface plasmon resonance have been applied. 

The signal generation principle of Raman is inelastic molecular light scattering, in contrast to resonant energy absorption/emission in IR spectroscopy. During the measurement, the sample is irradiated with intense monochromatic radiation. While most of this radiation is transmitted, refracted or reflected, a small amount is scattered at the molecules. 

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