Bulletin of the American Physical Society
74th Annual Gaseous Electronics Conference
Volume 66, Number 7
Monday–Friday, October 4–8, 2021;
Virtual: GEC Platform
Time Zone: Central Daylight Time, USA
Session BM24: Workshop IV: Electron Scattering Processes: Fundamentals, Challenges, Opportunities, and Advances |
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Chair: Sylwia Ptasinska, University of Notre Dame Room: Virtual GEC platform |
Monday, October 4, 2021 8:30AM - 9:10AM |
BM24.00001: Experimental Low Energy, Differential-Angle Electron Scattering from Atomic and Molecular Targets Invited Speaker: Murtadha A Khakoo Abstract: We will present experimental work done in the last 5 years in our laboratory at CSUF on the determination of differential cross sections (DCS) or DCS ratios for electron scattering from gaseous targets. The targets are: |
Monday, October 4, 2021 9:10AM - 9:50AM |
BM24.00002: Theory of Electron-Molecule Scattering and Dissociative Attachment1 Invited Speaker: Marcio Varella Electron-molecule collisions are described by Hamiltonians with continuum energy spectra, in contrast with conventional electronic structure problems which have discrete energy levels. Since computers can only handle discrete matrix algebra, the simulation of electron scattering by molecules is particularly challenging. We will present an overview of the available computational approaches to electronic collisions as well as their applications to contemporary problems in materials and life sciences. Special attention will be paid to low energy collisions and electron attachment. The formation of resonances (temporary negative ions) is known to initiate vibration dynamics that often leads to the dissociation of the molecular anions. This process, known as dissociative electron attachment (DEA), poses additional challenges to theory, since the continuum electronic problem is now coupled to the vibrational continuum defined by the dissociation problem. We will also discuss the recent adaptation of numerical methods developed for photo-induced nuclear dynamics to DEA dynamics. |
Monday, October 4, 2021 9:50AM - 10:00AM |
BM24.00003: Coffee Break Coffee Break |
Monday, October 4, 2021 10:00AM - 10:40AM |
BM24.00004: Experiments with Clusters: Unraveling solvation effects upon electron attachment Invited Speaker: Stephan Denifl Since more than two decades, there has been a significant interest in processes induced by low energy electrons in biologically relevant systems, especially in relation to DNA damage [1,2]. Ionizing radiation releases a large number of secondary electrons in cells. This secondary species with initial kinetic energies of up to few tens of eV may inelastically interact with building blocks of cells before they enter a (pre-)hydrated stage. It was shown that low energy electrons with energies < 15 eV can induce DNA damage in a film of plasmid DNA upon electron irradiation [1,2]. One of the underlying mechanisms of DNA damage on the molecular level was identified as dissociative electron attachment. Subsequently, a large number of experimental studies was carried out with isolated biomolecules in the gas phase [3]. In these mass spectrometric studies resonance energies as well as charged fragmentation products were determined. |
Monday, October 4, 2021 10:40AM - 11:20AM |
BM24.00005: Recent Advances in Ion Imaging Measurements of Electron-Molecule Interactions Invited Speaker: Daniel Slaughter Ion fragment momentum imaging experiments employing reaction microscopes [1,2] or velocity-slice imaging spectrometers [3], enable the highly differential momentum imaging of multiple fragment ions over large collection angles up to 4π steradians. These capabilities allow precise measurements of electron molecule interactions resulting in dissociation through the analysis of fragment ion kinetic energy and angular distributions. This information is particularly valuable for comparison with, or testing of, electronic structure calculations to predict the resonance energy and the kinetic energy released in dissociation, and electron scattering theory to predict the attachment or scattering probability in the body-fixed frame of the molecule. |
Monday, October 4, 2021 11:20AM - 12:00PM |
BM24.00006: Importance of Neutral Detection in Electron Scattering Processes Invited Speaker: Sylwia Ptasinska Over the past several decades, significant resources of the atomic, molecular, and optical physics community have been directed towards understanding collisional processes with molecular targets. Electron-molecule interactions are present in a plethora of physicochemical processes in any matter since low-energy electrons (LEEs) are the most abundant products of ionizing radiation and plasmas. LEEs during collisions at energies below ionization thresholds of the molecular target can be scattered elastically or lead to the rotational, vibrational, and electronic excitation or electron attachment to the target. The excitation and attachment can lead to the neutral dissociation or dissociative electron attachment (DEA) process, respectively. However, non-charged product identification has been particularly challenging due to technical limitations in neutral detection. In this tutorial, we will discuss a two-step electron ionization technique [1] that allows overcoming this challenge as well as other alternative techniques for neutral detection. |
Monday, October 4, 2021 12:00PM - 1:30PM |
BM24.00007: Lunch Break Lunch Break |
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