Ray Photoelectron ESCA Spectra

In contrast measurements of carbon Is electron binding energies in several hydrocarbons yielded a rather narrow range of chemical shifts. For instance, one cannot make a distinction between the carbon atoms of neopentane and those of benzene because their Is binding energies are virtually the same (290.4 eV). Ethane 

Electron spectra of carbenium ions were obtained in frozen superacid solutions or as isolated salts, generally in a 1 1 (v/v) SbFs-S02 solution. Sulfur dioxide was subsequently removed by the usual freeze-thaw procedure. A thin layer of the viscous SbFs solution was deposited on the precooled sample holder, in a dry nitrogen atmosphere. The spectra are recorded at liquid nitrogen temperature 38  

The binding energies Eb (defined as differences between the Fermi level and the Is atomic level energies) are given by the equation 

The lower traces in Fig. 3 represent the result given by a curve resolver. The peak area ratio is 1 3. 

The experimental carbon Is binding energy difference (3.9 eV) between the carbenium ion center and the remaining three carbon atoms is in the limit of that predicted by ab initio calculation (4.45 eV). Comparable results were obtained for the f-amyl cation (dEb+c c = 4 0.2 eV). 

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Fig. 5.32. X-ray photoelectron and x-ray emission spectra for BjO,. The O 2s and valence-band x-ray photoelectron (ESCA) spectra (obtained using A1 Ka radiation) are shown aligned with the oxygen K and boron K x-ray emission spectra ( soft x-ray spectra, SXS). Peak 1 in the ESCA spectrum is B Is peak II is O 2p. Spectra were aligned using li core-level binding energies (after Joyner and Hercules, 1980 reproduced with the publisher s permission).

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