Polarization ratios

The shapes of both /w and 7hv lines are assumed to be represented by simple Lorentzians. For a totally symmetric vibration with a low polarization ratio as in the present case, the vibrational and reorientational relaxation times Tv and can be determined from the half-widths of the isotropic and anisotropic spectra. Since the value of /hv is much smaller than that of /w for the 1050 cm" line, the contribution of /gv to the isotropic intensity can be neglected ... 

Integral intensities were obtained after dead-time corrections, background subtraction and normalization to averaged monitor counts. The Lp correction was applied in the usual way. Since the polarization ratio was not measured at BW5 so far, 90% linear horizontally polarized radiation was assumed for all scans. Calculations show that even a change in the beam polarization of 10% would effect the intensities of the highest order reflections of less than 1.5%. 

The polarized emission experiments on partially photooxidized aligned PF films indicate that the emission from the keto defects exhibits a somewhat smaller polarization ratio than the blue emission from the defect-free chains [263]. This observation was explained with the support of quantum mechanical calculations, which showed that the polarization of the fluorenone emission is influenced by local disorder [263]. 

Droplet temperature is of interest in practical spray processes since it influences the associated heat and mass transfer, chemical reactions, and phase changes such as evaporation or solidification. Various forms of Rayleigh, Raman and fluorescence spectroscopies have been developed for measurements of droplet temperature and species concentration in sprays.16471 Rainbow refractometry (thermometry), polarization ratioing thermometry, and exciplex method are some examples of the droplet temperature measurement techniques. 

Polarization ratioing thermometry has been proposed as a means of measuring the refractive index of a droplet and relating it to the droplet temperature. However, this approach does not have the... 

Characterization of the polarization state of fluorescence (polarization ratio, emission anisotropy)... 

In the expression of the polarization ratio, the denominator represents the fluorescence intensity in the direction of observation, whereas in the formula giving the emission anisotropy, the denominator represents the total fluorescence intensity. In a few situations (e.g. the study of radiative transfer) the polarization ratio is to be preferred, but in most cases, the use of emission anisotropy leads to simpler relations (see below). 

The components ly and Ih, vertically and horizontally polarized respectively, are such that Jz = Jy = Ix, Iy = IH (Figure 5.3). The total fluorescence intensity is then 2fy + Ih- The polarization ratio and the emission anisotropy are given by... 

The additivity law can also be expressed with the polarization ratio ... 

This relationship is called Perrin s equation, because it was established for the first time by Francis Perrin it was written at that time with polarization ratios... 

The observed and calculated (on the basis of the modified many-body model) wave numbers, the Raman intensities, and the polarization ratios for 1,4-dioxane 16 have been fully reported <1996MI401>. Eurther studies have shown that the frequencies of infrared (IR) C-H stretching vibration modes of 16 increase and the absorption intensities of the modes decrease with increasing water concentration <2003PGB3972>. 

C2H5/heptane/ buffer AOT/isooctane Ribonuclease A, cytochrome C, lysozyme Fisher s polarity ratio (P) linearly related to hydrophilic surroimdings at minimal AOT concentration for 100 % forward extraction. A procedure to estimate the AOT levels required for protein extraction was proposed [72]... 

Fig. 1.5.6 Polarization ratio of the scattered lighi against the angle for the unreacted titanium (IV) ethoxide, Ti(OEt)4, aerosol generated at 101°C, and the same aerosol reacted with water vapor at three distances (X) corresponding to 13, 39, and 340 ms reaction time. On the right-hand side are given calculated modal radii and refractive indices from the light scattering data. The bottom values are for the solid titania. (From Ref. 37.)...

Fig. 4 IPA (dashed line) and 2PA (solid line) spectra, and two-photon polarization ratio, (light dotted line) for phenylalanine, tyrosinamide, tryptophan. The abscissa corresponds to the excitation wavelength of the 2PA case. The IPA spectra are plotted at twice their excitation wavelength. The molecular structures are shown as insets in each graph. Reproduced with permission from [42]. 1993, Elsevier...

In the case of naphthalene, transitions to the two lowest excited states (again, often indicated with Lb and La) are two-photon forbidden, as in benzene. However, due to vibronic coupling, the Lb band is visible in the 2PA spectrum of naphthalene in the 575-650 nm region (see Fig. 5), while La gains intensity in the IPA spectrum and peaks around 275 nm [44-46], but is basically absent from the 2PA spectrum this is again in line with predictions based on the pseudoparity of the states. Polarization ratio data were used to aid the band assignment. A weak 0-0 peak of the Lb band can actually be seen in the 2PA spectrum (at 630.5 nm for naphthalene in cyclohexane [45] and at 631.8 nm in carbon tetrachloride [47]), probably because of local perturbation of the symmetry due to the solvent environment or other effects [44,45]. The 2PA... 

Fig. 5 Bottom 2PA spectrum for linearly polarized light (intensity in arbitrary units) and (top) polarization ratio of naphthalene in ethanol. 0-0 is the origin of the band (I), the La band (II) is not visible, and the numbers III-VI identify transitions to higher electronic states. The abscissa, representing the total excitation energy, is in units of cm". Reproduced with permission from [46]. 1981, Elsevier...

Linear polarization ratios have also been measured remotely. For example, results are given by Ward et al. (1973) and by Reagan et al. (1980). The sensitivity of scattering diagrams (Fig. 13.8), especially polarization (Fig. 13.9), to particle shape signals caution in inferring aerosol properties such as k from bistatic remote sensing. 

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