Raman scattering studies, determination

In LB films not only the interaction of chromophores but also their orientation can be controlled at the molecular level. Molecular orientation of chromophores has been determined by several methods including polarized UV/vis or IR absorption, second harmonic generation (SHG), Electron Spin Resonance (ESR), or resonance Raman scattering. We have measured the incident angle and polarization angle dependencies of polarized UV/vis absorption to study the molecular orientation of alloxazine, porphyrin, and carbazolyl chromophores, or 4,4 -bipyridinium radical cations in LB films[3-12]. Usually in-plane components of transition dipoles of chromophores are... 

Resonance Raman Spectroscopy. If the excitation wavelength is chosen to correspond to an absorption maximum of the species being studied, a 102—104 enhancement of the Raman scatter of the chromophore is observed. This effect is called resonance enhancement or resonance Raman (RR) spectroscopy. There are several mechanisms to explain this phenomenon, the most common of which is Franck-Condon enhancement. In this case, a band intensity is enhanced if some component of the vibrational motion is along one of the directions in which the molecule expands in the electronic excited state. The intensity is roughly proportional to the distortion of the molecule along this axis. RR spectroscopy has been an important biochemical tool, and it may have industrial uses in some areas of pigment chemistry. Two biological applications include the determination of helix transitions of deoxyribonucleic acid (DNA) (18), and the elucidation of several peptide structures (19). A review of topics in this area has been published (20). 

All data were processed by a central computer to derive both temperature and species concentrations. The details of these computer fits are identical to those described elsewhere (10, 11) with the exception that a vibrational partition function correction was included in the analysis of the data. The absolute mole fractions of fuel, 0 CO, H2, C0 , and H2O were determined by flowing known concentrations of these gases mixed with known concentrations of N2 through the burner. A comparison of the intensity of the N2 Raman spectrum intensity to the Raman spectrum intensity of any of the other gases provided an absolute calibration for all laser Raman scattering flame studies. 

Same laser for Raman and one optical tweezers 514.5 nm Microdroplets CH-stretching region 2,800-3,000 cm and C = C at 1,628 cm Mie and Raman scattering of microdroplet polymerization. Size, refractive index, and morphology are determined. Droplet evaporation and chemical reactions are studied... 

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