Collisional processes and details of atomic structure of heavy many-electron atoms and ions are not yet understood in a fully satisfying manner. Experimental studies are required for guiding new theoretical approaches. In response to fusion-related needs for collisional and spectroscopic data on tungsten atoms in all charge states, a project has been initiated in which electron-impact and photo...

Accurate modeling of impact-ionization is a critical issue for submicron devices. It is well known that models based on the electric field or on the average carrier energy give a rather poor description of the problem. We show that by accounting for the average square energy an accurate analytical description of the distribution function can be given which can then be used to evaluate microscop...

The formulation of the time-dependent close-coupling method is extended to allow the calculation of electron-impact triple-differential cross sections for atoms. The fully quantal method is applied to the electronimpact ionization of hydrogen at an incident energy of 54.4 eV for various scattering geometries. The timedependent close-coupling results are found to be in very good agreement with t...

Research into III-Nitride based avalanche photodiodes (APDs) is motivated by the need for high sensitivity ultraviolet (UV) detectors in numerous civilian and military applications. By designing III-Nitride photodetectors that utilize low-noise impact ionization high internal gain can be realized—GaN APDs operating in Geiger mode can achieve gains exceeding 1×10. Thus with careful design, it be...

Cross sections for single electron-impact ionization of formic acid (HCOOH) and acetic acid (CH3–COOH) are calculated using the binaryencounter-Bethe model in the energy range from the ionization threshold up to 4000 eV. The present results are compared with available experimental and theoretical data.

We have performed extensive close-coupling calculations to obtain total impact ionization cross sections of He atoms by antiprotons at energies from 1 keV to 300 keV by expanding the time-dependent two-electron wave functions in terms of helium eigenstates. The stability of the calculated ionization probabilities and total ionization cross sections with respect to the choice of basis functions ...

Methods and problems in the field of modern MOS-modeling are reviewed. Models for surface scattering and impact ionization, physical parameters which are of particular relevance for MOS-Transistor simulation programs, are explained. The various conceptional approaches for the numerical solution of the classical semiconductor equations are compared. An example of application of a simulation prog...

We present data from the sixth Cassini flyby of Titan (T5), showing that the magnetosphere of Saturn strongly interacts with the moon’s ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement with the altitude structure of the ionosphere. Furthermore, we suggest that the dense and cold exo-ionosphere (from the exobase at 1430 km and outward to several T...

Measurements of electron capture and ionization of O2 molecules in collisions with H + and O ions have been made over an energy range 10–100 keV. Cross sections for dissociative and nondissociative interactions have been separately determined using coincidence techniques. Nondissociative channels leading to O2 product formation are shown to be dominant for both the H and the O projectiles in th...

We have carried out measurements on metastable fragmentation of mass selected argon cluster ions which are produced by electron impact ionization of a neutral argon cluster beam. From the shape of the fragment ion peaks (MIKE scan technique) one can deduce information about the distribution of kinetic energy that is released in the decay reaction. In this study, for Ar+5 to Ar + 15, it is Gauss...