Swarm analysis of electron transport in biomolecules: Water and THF
| Autor: | Urquijo, J. de, Casey, M., Konvalov, D., Brunger, M.J., García, Gustavo, Petrovic, Z., White, R.D. |
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| Rok vydání: | 2015 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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