He II photoelectron spectra of La, Ce and Yb show features which cannot be explained in terms of single electron excitations. It is proposed that these are due to formation of electron-hole paris.

L₃VV Auger transitions of copper alloys show a feature due to a band-like states, the shape and intensity of which depend on the composition. The energy separation between this feature and the L₃M_4·5M_4·5 peak increases progressively with Cu concentration.

The observed O 1s X-ray photoemission spectra of the cuprate superconductors often exhibit a satellite at a higher binding energy to the main peak. The origin of this satellite is not fully understood. We have done model cluster calculations to investigate the origin of this satellite using the configuration interaction approach. The calculated spectra for the divalent and superconducting cuprates essentially exhibit a single peak. On distorting the cluster in-plane, the peak shifts to higher binding energies. This substantiates a deterioration of the surface leading to the observed satellite structure in the O 1s core-level photoemission spectra of the cuprate superconductors.

We review the unusual structural, transport and magnetic properties of highly conducting polyaniline, doped with boron trifluoride. Our studies establish the unique conducting state of this system, which is in distinct contrast with the conventional proton-doped polyaniline samples.