Optical absorption intensity

Scheme 9.18 Top Plots of optical absorption intensity as a function of wavelength and electrode potential in the Sii region for K[h-NT]. In all plots, raw electrochemical data, that is, uncorrected for ohmic drop, are referenced to SCE. Bottom Chirality map displaying the average standard potentials associated to each SWNT. HiPco SWNTs are located inside the red line, while arc-discharge SWNT are inside the blue line. Starred values were extrapolated from the linear fitting equations given in the text. (See the color version of this Scheme in Color Plates section.)...

B.R. Judd, Optical Absorption Intensities of Rare Earth Ions, Phys. Rev., 127, 750-61(1962). 

B. R. Judd, Optical absorption intensities of rare-earth ions. Physical Review, 127, 750-761 (1962). 

S. Edvardsson, M. Wolf, and J. O. Thomas, Sensitivity of optical-absorption intensities for rare-earth ions. Physical Review B, 45, 10918-10923 (1992). 

For a simplified case, one can obtain the rate of CL emission, =ft GI /e, where /is a function containing correction parameters of the CL detection system and that takes into account the fact that not all photons generated in the material are emitted due to optical absorption and internal reflection losses q is the radiative recombination efficiency (or internal quantum efficiency) /(, is the electron-beam current and is the electronic charge. This equation indicates that the rate of CL emission is proportional to q, and from the definition of the latter we conclude that in the observed CL intensity one cannot distii pish between radiative and nonradiative processes in a quantitative manner. One should also note that q depends on various factors, such as temperature, the presence of defects, and the... 

It should be noted that during CL observations intensity variations may arise due to sample morphology (e.g., surface roughness), which may lead to nonuniform excitation and to local variations in optical absorption and reflecdon losses. 

In the following sections, we first show the phonon dispersion relation of CNTs, and then the calculated results for the Raman intensity of a CNT are shown as a function of the polarisation direction. We also show the Raman calculation for a finite length of CNT, which is relevant to the intermediate frequency region. The enhancement of the Raman intensity is observed as a function of laser frequency when the laser excitation frequency is close to a frequency of high optical absorption, and this effect is called the resonant Raman effect. The observed Raman spectra of SWCNTs show resonant-Raman effects [5, 8], which will be given in the last section. 

The infra-red measurements were of two types, normal-film measurements with the sample sandwiched between KBr plates, and tilted-film experiments with the sample sandwiched between 45° prisms of KBr, in each case with layers of Nujol to provide optical matching. Whereas the 1616 cm 1 Raman line occurs in a region well clear of other lines so that it was satisfactory to measure peak intensities, the infra-red spectrum of PET shows many overlapping bands. Accurate assessment of absorption intensities therefore requires the computer separation of the spectrum into a set of overlapping peaks (shown to be Lorentzian in profile) and a linear background. The procedures adopted and the band assignments are discussed in detail by Hutchinson et al. 6). 

In view of this the divalent lanthanide ions are expected to show intense optical absorption in the whole visible region in compounds containing M(d°) ions. Since these compounds are not easy to prepare, our earlier warning is relevant. Only results on well-prepared and characterized compounds may be... 

SHG, more so than other optical techniques, can give deceptive results due to propagation phenomena. Disregarding for the moment optical absorption effects, non-phase-matched SHG displays the behavior pictured in Figure 2 (18). The harmonic intensity I w emerging from a sample depends on the sample thickness / in a... 

Measurements of binding curves without influencing the equilibria can be performed if the readout for complex formation is correlated with a change in a macroscopic signal. This can be either a change in fluorescence intensity, fluorescence polarization, optical absorption, or heat of association (see next chapter). Assume an equilibrium... 

The oxidized active enzyme is intensely green and exhibits an unusual optical absorption spectrum (123,124) shown in Fig. 7. It is dominated by an intense maxi-... 

Type 1 Cu(II) intense (e > 3000 M 1 cm ) blue (2max 600 nm) optical absorption band EPR spectrum with an uncommonly small hyperfine splitting in gn region. 

The imaginary part of the dielectric function describes the optical absorption in PS and thereby gives information about the bandgap. Details of the optical transitions responsible for absorption and emission of photons in Si are shown in Fig. 7.12 and will be discussed in the next section. The absorbed fraction P(x) of the non-reflected light intensity P depends on the sample thickness % and on the absorption coefficient a according to... 

Recoilless Optical Absorption in Alkali Halides. Recently Fitchen et al (JO) have observed zero phonon transitions of color centers in the alkali halides using optical absorption techniques. They have measured the temperature dependence of the intensity of the zero phonon line, and from this have determined the characteristic temperatures for the process. In contrast to the Mossbauer results, they have found characteristic temperatures not too different from the alkali halide Debye temperatures. 

Figure 1,17 Absorption spectrum of a forsteritic olivine under polarized light. Ordinate axis represents optical density (relative absorption intensity, ///q). From R. G. Burns (1970), Mineralogical Applications of Crystal Field Theory. Reprinted with the permission of Cambridge University Press.

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