A.K.F. Haque

Generalized Kolbenstvedt model for electron impact ionization of the K-, L- and M-shell ions

The recently proposed generalized Kolbenstvedt model (GKLV) of Haque et al (2007 Eur. Phys. J. D 42 203), for the electron impact ionization (EII) of atoms, was applied to a wide range of K-, L- and M-shell electrons of ionic targets from threshold to 1 MeV incident energy. The set of species-independent parameters, two for each of the ionized orbits, is the same as that for neutral targets, and provides an excellent account of the EII cross-sectional data for 36 ions, including those belonging to Li, Be, B, C, N, O and Ne electronic sequences as well as those having 3s-, 3p- and 3d-configurations of the M-shell in a consistent manner. The performance of GKLV is found to be better than that of the modified version of the BELL model (Haque et al 2006 Phys. Rev. A 73 052703, Haque et al 2006 Phys. Scr. 74 377).

Electron impact secondary electron emissions from atomic and molecular solid targets

Synopsis The Sternglass theory [Sternglass, Phys. Rev. 108, (1957) 1] for fast-ion-induced secondary electron emission, which is proportional to the stopping powers, has been modified to calculate the electron impact secondary electron yield from both elemental and compound targets with atomic number Z = 4 92 for incident energy range 5 10 5   i E eV. This modification includes the use of a realistic stopping power expression that involves calcula-

Electron impact L and M-subshell ionization cross sections for atoms (14 ≤ Z ≤ 92) including the relativistic effects

Synopsis Electron impact inner-subshell (L and M) ionization cross sections for various atoms (14≤ Z ≤92) are calculated and compared with experimental and other theoretical results. The electron impact ionization cross sections (EIICS) are needed in various fields ranging from biological to chemical, plasma to astrophysics, and laser to medical physics. At energies above the breakup threshold the scattering in a three-body system remains a most challenging quantum mechanical problem. For simpler targets, like H and He, there are few accurate calculations available but for many electron targets it is rather disappointing. Experimental data for the K-shell ionization are rife; they are, however, limited for both the L-shell and M-shell but their subshell data [1] are practically zero. On the other hand the huge demands for EIICS in applications cannot be fulfilled easily by generating a database either by experimental or by quantal studies. So resorts are made to fulfill this void by using simple–to-use models that must yield accurate results. In this study we report few such models that are capable of describing reasonably the experimental data for a wide range of atomic targets over a wider energy domain. Two easy-to-implement models, namely XMCN [1,2] and XMUIBED [1], are presented here; the former modifies the DM relativistic factor of the MCN model with a Z-dependent factor, while the latter replaces the Bethe part of the BED model by a simple two-parameter Born term. Both the XMCN and XMUIBED models, however, generate reliable EIICS quickly. Our results in Fig. 1 are compared with the experimental data and found good agreements for Land M-subshell.

Electron impact M-subshell ionization of atoms at relativistic energies

We propose an extension of our recently modified simplified-improved-binary-encounter dipole (MUIBED) model [1] suitable even for relativistic energies. This new model (XMUBED) is applied to calculate the electron impact single M-subshell ionization cross-sections for atomic targets with various charges Z (79 ≤ Z ≤ 92). The parameters of the MUIBED model for the M-shell ionization calculations are modified to account well for fourteen atomic targets (between Au and U) for the inner M-subshell ionization cross sections.

Theoretical electron impact ionization cross sections for atomic and ionic targets for E≤10 keV

Electron impact ionization cross sections for E ≤ 10 keV are presented for O and its isoelectronic series (F+, Ne2+ and Si6+ ions) and compared with experimental and other theoretical results.