Fano line shapes

Figure 26. Comparison of the resonance scattering from H atoms or H+ obtained by fitting the Fano line shape in HCIO4 (open squares) and H2SO4 (closed squares) with the adsorbed hydrogen coverage (closed circles) and sulfate adsorption (open circles) obtained by cyclic voltammetry. (Reproduced with permission from ref 50. Copyright 2001 The Electrochemical Society, Inc.)...

Fig. 3.36. Fano line shapes fitted to the measured absorption profile of the Ri (0) transition of HD at 77 K for densities from 28 to 138.5 amagat. Reproduced with permission by the National Research Council of Canada from [345].

Free carriers change Raman spectra, either by single particle contribution to the spectrum, or by phonon- plasmon interaction. In addition, interference of electronic transition continua with single phonon excitations may lead to Fano line shapes, as mentioned in the introduction. The Fano effect is encountered in p-doped Si crystals, as shown in Fig. 4.8-19. The shown lines correspond to the respective Raman active mode at 520 cm for crystals with 4 different carrier concentrations, excited with a red laser. The continuous line is calculated according to Eq. 4.8-6. Antiresonance on the low frequency side and line enhancement on the high frequency side are a consequence of the positive value of Q. A reverse type of behavior is possible in the case of a negative Q. 

Fig. 18b. Fit of the partial cross sections from fig. 18a given by dots to Fano line shapes drawn solid and to the calculations of Zangwill and Seven (1980) drawn dashed. (After Gerken et al. 1982.)...

Interference between different ways of reaching the same product state will be a key element in our discussion of control in later chapters. The Fano line shape is a special case where the alternative routes have a clear physical interpretation, one being direct scattering... 

Another type of such coupling is the configuration interaction (CI) between a true discrete excitation and a continuum excitation. This autoionization phenomenon is clearly within the TDLDA framework, A nice example can be found in copper where 3d -> ef, ep excitations interfere with the 3p -> 4s transition, The resulting 3d partial photoionization cross section is shown in Figure 8, In addition to the prominent Fano line shape, an overall diminultion (relative to the LDA) of the cross section is found due to intrashell 3d polarization. The interesting dip around 80 eV is again a Cl effect, but this time the 3d ef,ep excitations interfere with the continuum channels, 3p es,ed. 

Boron dooins concentration. The Fano line shape is correlated with the boron doping. It is characterized by an upward shift on the high wavenumber side of the peak (Fig. 5.5). A slight variation in the intensity of the upward shift of the 1332 cm line is observed with increase of the boron concentration [2]. 

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