Electron spectroscopic determinations ofMandNcore-hole lifetimes for the elements Nb—Te (Z=41−52)

Abstract

Photoelectron spectroscopy has been used to determine $M$ and $N$ core-level widths for the elements Nb—Te ($Z=41-52\mathrm{}$). The analysis is based on direct comparisons of the lifetime contributions to different core levels. Absolute determinations are made for the narrow $3d$ levels. In the metals Nb—Rh ($Z=41-45\mathrm{}$) an $M_4{M}_5{N}_{45}$ Coster-Kronig decay channel is observed through a broadening of the $3d_{\frac{3}{2}}$ core-electron lines. The rate of this Coster-Kronig process is found to have its maximum for Ru and Rh. For Pd a much reduced, but still significant, broadening of the $3d_{\frac{3}{2}}$ level is detected. This observation is discussed in terms of itinerant versus quasiatomic contributions to the Coster-Kronig process. For $Z\ge 47$ (Ag) the Coster-Kronig channel is closed. For Nb—Rh the $M_4{M}_5{N}_{45}$ process can be used for absolute determinations of the $3d$ linewidths. In this connection also the properties of the $M_{45}{N}_{45}{N}_{45}$ Auger process are discussed. The accuracy of the present method makes it possible to investigate small differences between the $3p_{\frac{1}{2}}$ and $3p_{\frac{3}{2}}$ level widths. For several elements the unusual result is obtained that the $3p_{\frac{3}{2}}$ level is broader than the $3p_{\frac{1}{2}}$ level. This finding is in good agreement with theoretical predictions. The $4s$ and $4p$ spectra of the currently investigated elements are strongly influenced by configuration-interaction (CI) effects. However, the $4s$ line shapes are found to be quite normal for all the 5th-period elements. For $Z\le 45$ (Rh) the $4p_{\frac{1}{2}}$ level is found to be broadened due to $N_2{N}_3{N}_{45}$ super-Coster-Kronig processes. For $Z\le 46$ (Pd) the shape of the $4p_{\frac{3}{2}}$ core-electron lines can reasonably well be reproduced by broadened $3d_{\frac{5}{2}}$ line profiles. For $Z\ge 47$ (Ag) this can, however, not be achieved. This marks a transition into a...