Electron impact cross-sections for biomolecules ¿ completeness and selfconsistency via swarm analysis

ICPEAC 2015, Toledo, Spain on 22 –28 July 2015; http://www.icpeac2015.com/The accuracy and completeness of electron impact cross-sections in water and tetrahydrofuran are assessed through comparison with experimental electron transport coefficients using the pulsed Townsend experiment.Peer Reviewe

Swarm analysis of electron transport in biomolecules: Water and THF

POSMOL 2015, 17-20 July 2015, Lisboa, Portugal; http://eventos.fct.unl.pt/posmol2015/The determination of a comprehensive set of electron-biomolecule cross-sections is fundamental to understanding electron induced processes arising in plasma medicine and radiation damage modelling. Formulation of complete sets is generally based on a critical assessment of available experimental `beam' studies and theoretical calculations, and interpolations/extropolations. Issues of completeness and accuracy of cross-section sets arise and it is here that swarm experiments play a key role. Here, excess electrons under the action of an applied electric field are passed through a gas of biomolecules and measured currents are interpreted in terms of transport coefficients such as drift velocities, diffusion coefficients, and ionization/attachment rates. Through comparison of measured transport coefficients with those calculated from transport theory/ simulation, one can assess the ability of the cross-section set to accurately treat particle, momentum, and energy balance. In this presentation we report on recent swarm measurements in the biomolecules of water and tetrahydrafuran (THF) using the pulsed-Townsend technique of the de Urquijo group. We present and assess the consistency of cross-section sets for water and THF through a comparison of calculated transport coefficients using a multi-term Boltzmann equation solution with the available experimental swarm measurements provides a discriminating test on consistency and accuracy of the cross-section. Cross-section degeneracy (i.e., different sets of cross-sections can produce the same field dependence of the transport coefficients) is an issue. Additional handles to assess the degeneracy, accuracy and completeness of the cross-section set can be through measurements in admixtures with well known cross-sections which can considerably modify the distribution function. To this end, results for water/He, water/Ar and THF/N2 mixtures will be presented.Peer Reviewe

Electron impact cross-sections for biomolecules - completeness and self-consistency via swarm analysis

The accuracy and completeness of electron impact cross-sections in water and tetrahydrofuran are assessed through comparison with experimental electron transport coefficients using the pulsed- Townsend experiment