Raman scattering, characteristics

In the pioneering work the same information was extracted from the extremum position assuming it is independent of y [143]. This is actually the case when isotropic scattering is studied by the CARS spectroscopy method [134]. The characteristic feature of the method is that it measures o(ico) 2 not the real part of Ko(icu), as conventional Raman scattering does. This is insignificant for symmetric Lorentzian contours, but not for the asymmetric spectra observed in rarefied gas. These CARS spectra are different from Raman ones both in shape and width until the spectrum collapses and its asymmetry disappears. In particular, it turns out that... 

Recently, the In situ Raman scattering from Fe-TsPc adsorbed onto the low Index crystallographic faces of Ag was examined and the results obtained are shown In Fig. 5 (15). On the basis of the similarities of these spectra with those obtained for the macrocycle In solution phase, as well as the polarization behavior characteristics, It has been concluded that the most likely configuration Is that with the macrocycle edge-on with respect to the surface. This Is In agreement with conclusions reached from the UV-vlslble reflectance spectra. The preferred configuration, however, may depend on the particular macrocycle, as well as on the nature of the adsorption site. 

The interactions of photons with molecules are described by molecular cross-sections. For IR spectroscopy the cross-section is some two orders of magnitude smaller with respect to UV or fluorescence spectroscopy but about 10 orders of magnitude bigger than for Raman scattering. The peaks in IR spectra represent the excitation of vibrational modes of the molecules in the sample and thus are associated with the various chemical bonds and functional groups present in the molecules. The frequencies of the characteristic absorption bands lie within a relatively narrow range, almost independent of the composition of the rest of the molecule. The relative constancy of these group frequencies allows determination of the characteristic... 

Kaiser, T. Roll, G. Schweiger, G., Investigation of coated droplets in an optical trap Raman scattering, elastic light scattering, and evaporation characteristics, Appl. Opt. 1996, 35,... 

The first term on the right-hand side of Equation (1.24) accounts for the generated intensity due to Rayleigh scattered light, while the second term is related to the intensity of the Raman scattered light. For visible light coo 10 Hz, while the characteristic phonon frequencies are much shorter, typically 12 10 Hz. Then coq and the intensity of Raman scattering varies as coq, as stated in point (iv) above. 

Kim, N.H. and Kim, K. (2006) Adsorption characteristics of arylisocyanide on Au and Pt electrode surfaces surface-enhanced Raman scattering study. ]. Phys. Chem. E, 110, 1837-42. 

An illustrative example of the influence of symmetry on the number of vibrations is provided by the homologous series of cyclic sulfur allotropes S (n = 6-12). The IR absorptions for these ring systems are weak owing to the low polarity of S-S bonds. However, sulfur is a good Raman scatterer because S-S bonds are readily polarised. The various sulfur allotropes have different symmetries in addition to a different number of sulfur atoms and, consequently, each allotrope exhibits a characteristic Raman spectrum (Figure 3.8). ... 

The mechanism of control with multipulse excitation is likely due to dynamics of the carotenoid donor. The presumably incoherent EET process [1] would not support the observed dependence on the carrier phase via the parameter c. Furthermore, the control effect does not suffer from annihilation at higher excitation intensities [2], as would be characteristic for the delocalised excitons in the B850 ring [1], However, it is well known that femtosecond pulses populate higher ground state vibrational levels by impulsive Raman scattering (IRS) [4], and that the periodic phase modulation (Eq. 1) makes IRS selective for specific vibrations... 

The work reported here shows that the transformation temperature in the LaVxNbi x04 system is significantly affected by the simple, partial substitution of one 5+ ion for another at the center of the tetrahedron. This effect is connected closely to the dynamical characteristics of the crystal lattice. A study involving inelastic neutron scattering, heat capacity and Raman scattering is under way in this Laboratory to clarify these aspects of the problem. 

A vibrational spectrum provides something like a structural fingerprint of matter because it is characteristic of chemical bonds in a specific molecule. Therefore, imaging based on vibrational spectroscopic signatures, such as Raman scattering and IR absorption, provides a great deal of molecular structural information about the target under study. 

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