Deconvolution asymmetric

The relatively poor resolution of the XPS systems has lead to an extensive use of deconvolution techniques in order to prove the presence of shifted core levels of low intensity in the presence of unshifted levels (thin oxide layers on metal substrates). Deconvolution techniques should be used only in those cases where the presence of multi components is shown up by a shoulder in the intensity distribution. Interpretation of asymmetric peaks in terms of chemical shifts can be misleading in some cases because the asymmetry may change due to a change of the electron population at the Fermi level as was demonstrated for the metallic oxide Ir02 [23, 24],... 

The analysis of the shape of the heat emission peaks in the above studies indicated that peaks typical of fast chemisorption processes became more asymmetric for moderate coverages. This indicated that an activated process started at those coverages superimposed on a nonactivated step. IR spectroscopy verified this conclusion. Della Gatta et at. (112) showed that such a peak can be deconvoluted by subtracting from it a peak of the same height from the second adsorption run for which the adsorption is reversible. 

The caldned samples showed little or no iron oxide phases. The spectra at RT and 78 K of all samples were quite similar and indicated that the iron was in the ferric state. The RT spectra were somewhat asymmetric with an average IS of 0.29 mm s" which may indicate the presence of both octahedral and tetrahedral iron. The spectra could be deconvoluted into two doublets with one doublet for tetrahedral iron with an IS of 0.23 mm s and the other doublet for octahedral iron with an IS of 0.33 mm s . ... 

Examination of the nature of randomisation processes is still in its infancy, both on the experimental and theoretical fronts. The most straightforward experimental approach has been that of the formation of highly energetic symmetric molecules from unsymmetric precursors, followed by the observation of an asymmetric formation of products [71.R2 81.L]. Next, we have many examples nowadays, e.g. [81.L 82.S4], where non-statistical energy distributions are observed either in or between the products formed in unimolecular fragmentation reactions these observations contain information about the degree of randomisation in the reactant molecule, but the deconvolution of such experimental data to obtain that information is likely to be a formidable task [81.P2]. Finally, we have a rapidly growing array of laser-based experiments which probe the dynamics of the molecular motions subsequent to the initial excitation, see e.g. [81J]. 

It is possible to use multiple sine waves [10] and so extract as a Fourier series (or other deconvolution procedure) the response to several frequencies simultaneously, as illustrated in Chapter 4. An extension of this is the use of saw-tooth temperature modulations [20]. These can be considered to be a combination of an infinite series of sine waves (though only a limited range will be available in practice). A symmetric saw-tooth (same heating and cooling rate) only has odd harmonics, but an asymmetric saw-tooth (different heating and cooling rates) is equivalent to a broad range of frequencies. 

Spinach BBY-grana and LHCII were prepared and their room temperature absorption spectra were deconvoluted in asymmetric gaussian components as described in (10). 

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