P. C. Deshmukh

Beyond the dipole approximation: angular-distribution effects in valence photoemission

Angular distributions of valence photoelectrons showing effects due to higher-multipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 - 1200 eV photon-energy range studied. The results suggest that any photoemission experiment, on any sample, can be affected at relatively low photon energies, pointing to a general need for caution in interpreting angle-resolved-photoemission measurements.

Relativistic and confinement effects in photoionization of Xe

The effect of a spin–orbit interaction activated interchannel coupling in 4d photoionization channels of Xe on the 5s photoionization amplitudes is studied and analysed. The dramatic effect of confinement of the Xe atom in a C60 cage on the 4d photoionization parameters and the consequent effect on 5s photoionization via an interchannel coupling are also discussed.

Pronounced effects of interchannel coupling in high-energy photoionization

The 3d core level photoemission of metallic Ag and In was measured over a wide energy range including the 2p ionization thresholds. The intensities (photoionization cross sections) of the 3d5/2 and 3d3/2 lines were observed to modulate significantly with photon energy, both absolute and relative, and this is most pronounced in the vicinity of the 2p thresholds, i.e., at photon energies about an order of magnitude above the 3d thresholds. Calculations based on the relativistic-random-phase approximation show that this effect is due to interchannel coupling of the 3d photoionization channels with the 2p channels affecting the cross section over a wide range of energies. It is argued that this is a general phenomenon in high-energy photoionization throughout the periodic table.

MS Xα calculations on the valence auger spectrum of CO

Abstract We have examined the utility of the MS Xα method of calculation of molecular electronic structure, in the transition-state model, as a tool in the analysis of valence Auger spectra, using CO as a test case. The method is not especially reliable in prediction of final-state energies, but serves reasonably well in prediction of the many-electron contribution to the final-state energies and in prediction of intensities.

RELATIVISTIC EFFECTS IN THE PHOTOIONIZATION OF ATOMIC BERYLLIUM

Calculations of the cross section, angular distribution asymmetry parameter and photoelectron spin-polarization parameters for valence photoionization of neutral beryllium using the relativistic-random-phase approximation plus relativistic-multichannel quantum defect theory are performed in the region of Rydberg resonances just below the 1s ionization threshold. A new autoionizing series, 1s2s2np 3P, which occurs solely due to relativistic effects, is found. A quantitative study of the character of resonances has been carried out and the implications of these relativistic resonances for angular distributions and spin polarization are investigated in detail.

Attosecond time delay in the photoionization of endohedral atoms A@C 60 : A probe of confinement resonances

The effects of confinement resonances on photoelectron group delay (Wigner time delay) following ionization of an atom encapsulated inside a C

Relativistic calculations of angle-dependent photoemission time delay

_{60}

Photoionization of atomic krypton confined in the fullerene C60

cage have been studied theoretically using both relativistic and non-relativistic random phase approximations. The results indicate clearly the resonant character of the confinement oscillations in time delay of the

Theoretical and experimental demonstrations of the existence of quadrupole Cooper minima

4d

Relativistic Effects in Atomic and Ionic Photoionization: “Anomalous” Behavior at the Low End of Isoelectronic Sequences

shell of Xe@C