Photoemission peaks, multiplet

Another final-state effect which gives rise to an increase in the number of photoemission peaks is multiplet splitting. If the valence levels contain unpaired... 

The only UPS/XPS photoemission study of Am shows a lanthanide like valence band feature as displayed in Fig. 16. The 5f emission is nearly completely withdrawn from Ep except possibly for some very weak 5 f contribution seen only in high resolution He-I-spectra (AE 0.12 eV) as a very sharp peak just at Ep. The 5 f intensity is concentrated in a structured peak around 2.8 eV binding energy (for MgR excitation, upper curve, the structures are not resolved) as deduced from the excitation energy dependence of the spectra. If one compares with Sm metal, the peaks at 1.8, 2.6 and 3.2 eV are attributed to the H, F, and P states, respectively, of the 5f final state multiplet originating from the initial 5f ground state of trivalent Am. 

On the basis of the known electronic properties of actinides (which have been discussed elsewhere in this book), theoreticians had distinguished the 5f itinerant behaviour of light actinide metals from the 5 f localized behaviour of heavy actinide metals from Am on. The crossover, presented often as a Mott transition, had been predicted to occur between Pu and Am metal, due to the localized character of the 5f state in the latter. Photoemission spectroscopy demonstrates this phenomenon directly with the observation of a 5 f multiplet away from the Fermi level. The detailed description of this peak is certainly complicated, as often happens for response of localized states in photoemission on the other hand (Fig. 17) the contrast to the emission of Pu metal is convincing. 

Cls photoemission shakeup satellites for the CO molecule were calculated with the spin-polarized discrete variational Xa method. The transition state method was applied to the estimation of multiplet peak positions for the shakeup transitions and the results are in reasonable agreement with the experimental values. 

Multiplet splitting of core level peaks can occur when the photoemitting atom has unpaired valence electrons. For example, consider the photoemission of an electron from an s-level. After photoionization, the remaining impaired electron will either have spin parallel or antiparallel to the unpaired valence electrons. This results in two... 

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