M Leung

Bio: M Leung is an academic researcher. The author has contributed to research in topics: Polarizability & Dipole. The author has an hindex of 1, co-authored 1 publications receiving 38 citations.

Excitation of electronic states in tetrahydrofuran by electron impact.

Abstract: We report on differential and integral cross section measurements for the electron impact excitation of the three lowest lying Rydberg bands of electronic states in tetrahydrofuran. The energy range of the present experiments was 15–50 eV with the angular range of the differential cross section measurements being 15°–90°. The important effects of the long-range target dipole moment and the target dipole polarizability, on the scattering dynamics of this system, are evident from the present results. To the best of our knowledge, there are no other theoretical or experimental data against which we can compare the cross section results from this study.

Electron scattering from molecules and molecular aggregates of biological relevance

Abstract: In this Topical Review we survey the current state of the art in the study of low energy electron collisions with biologically relevant molecules and molecular clusters. We briefly describe the methods and techniques used in the investigation of these processes and summarise the results obtained so far for DNA constituents and their model compounds, amino acids, peptides and other biomolecules. The applications of the data obtained is briefly described as well as future required developments.

Modelling low energy electron and positron tracks in biologically relevant media

Abstract: This colloquium describes an approach to incorporate into radiation damage models the effect of low and intermediate energy (0-100 eV) electrons and positrons, slowing down in biologically relevant ma- terials (water and representative biomolecules). The core of the modelling procedure is a C++ computing programme named "Low Energy Particle Track Simulation (LEPTS)", which is compatible with available general purpose Monte Carlo packages. Input parameters are carefully selected from theoretical and ex- perimental cross section data and energy loss distribution functions. Data sources used for this purpose are reviewed showing examples of electron and positron cross section and energy loss data for interactions with different media of increasing complexity: atoms, molecules, clusters and condense matter. Finally, we show how such a model can be used to develop an effective dosimetric tool at the molecular level (i.e. nanodosimetry). Recent experimental developments to study the fragmentation induced in biologically material by charge transfer from neutrals and negative ions are also included.

Electron scattering and transport in biofuels, biomolecules and biomass fragments

Abstract: We review a selection of recent experimental and theoretical cross section results for electron scattering from a range of biofuels (methanol, ethanol), biomolecules (water, tetrahydrofuran, pyrimidine, tetrahydrofurfuryl alcohol and para-benzoquinone) and molecular fragments that are formed from the action of atmospheric-pressure plasmas on biomass (phenol, furfural). Where possible, the implications of those cross sections, on simulating the transport of electrons through such a species under the influence of an applied external electric field or in the context of charged-particle track behaviour and radiation damage in matter, will also be examined.

Total, elastic, and inelastic cross sections for positron and electron collisions with tetrahydrofuran

Abstract: We present total, elastic, and inelastic cross sections for positron and electron scattering from tetrahydrofuran (THF) in the energy range between 1 and 5000 eV. Total cross sections (TCS), positronium formation cross sections, the summed inelastic integral cross sections (ICS) for electronic excitations and direct ionization, as well as elastic differential cross sections (DCS) at selected incident energies, have been measured for positron collisions with THF. The positron beam used to carry out these experiments had an energy resolution in the range 40–100 meV (full-width at half-maximum). We also present TCS results for positron and electron scattering from THF computed within the independent atom model using the screening corrected additivity rule approach. In addition, we calculated positron-impact elastic DCS and the sum over all inelastic ICS (except rotations and vibrations). While our integral and differential positron cross sections are the first of their kind, we compare our TCS with previous literature values for this species. We also provide a comparison between positron and electron-impact cross sections, in order to uncover any differences or similarities in the scattering dynamics with these two different projectiles. © 2013 American Institute of Physics.