Bulletin of the American Physical Society
72nd Annual Gaseous Electronics Conference
Volume 64, Number 10
Monday–Friday, October 28–November 1 2019; College Station, Texas
Session ET1: Electron Molecule Collisions |
Hide Abstracts |
Chair: Mark Zammit, LANL Room: Century I |
Tuesday, October 29, 2019 1:45PM - 2:15PM |
ET1.00001: Low energy differential angle electron impact scattering from molecular hydrogen and carbon monoxide Invited Speaker: Mutardha Khakoo The electron impact elastic scattering and electronic excitation of molecular hydrogen and excitation of carbon monoxide at low incident energies using both conventional electrostatic electron spectrometry [1,2] and time-of-flight electron spectrometry [3] will be presented. The differential scattering data will be compared with close-coupling theoretical work, which has shown very good to excellent agreement with the present work In the case of H$_{2}$ , this is the convergent close-coupling work of the Curtin University group [4] and for CO this is the molecular ${R}$-matrix of Tennyson and co-workers [5]. Recent progress in this area of electron- molecule differential scattering will also be presented. \\ \\ In collaboration with: Leigh Hargreaves and Mateusz Zawadzki, Gdansk University of Technology \\ \\ $[1]$ Low energy elastic scattering of electrons from H$_{2}$ and N$_{2}$ , J. Muse, H. Silva, M. C. A. Lopes and M. A. Khakoo, J. Phys. B 41 095203 (2008). \\ $[2]$ Differential cross sections for excitation of H$_{2}$ by low-energy electrons, L. R. Hargreaves, S.Bhari, B. Ajdari, X. Liu, R. Laher, M. Zammit, J. S. Savage, D. V. Fursa, I. Bray and M. A.Khakoo, J. Phys. B, 50 225203 (2017). \\ $[3$] Time-of-flight electron scattering from molecular hydrogen: Benchmark cross sections for excitation of the $X^{1} \Sigma_{g} ^{+} \rightarrow b^{3} \Sigma_{u} ^{+}$ transition, M. Zawadzki, R. Wright, G. Dolmat, M. F. Martin, L.Hargreaves, D. V. Fursa, M. C. Zammit, L. H. Scarlett, J. K. Tapley, J. S. Savage, I. Bray and M.A. Khakoo, Phys. Rev. A 97 050702(R) (2018). \\ $[4]$ Complete Solution of Electronic Excitation and Ionization in Electron-Hydrogen Molecule Scattering, M. C. Zammit, J. S. Savage, D. V. Fursa, and I. Bray, Phys. Rev.Lett. 116, 233201 (2016). \\ $[5]$ On-going collaboration with Professor Jonathan Tennyson (University College London, UK), Dr. Amar Dora (North Orissa University, India), Dr. Zdenek Masin (Charles University, Prague, Czech Republic) (2018-). [Preview Abstract] |
Tuesday, October 29, 2019 2:15PM - 2:30PM |
ET1.00002: Dissociative electron attachment to ring-containing compounds Sylwia Ptasinska, Zhou Li, Michal Ryszka, Ian Carmichael In order to draw a comprehensive picture of gas-phase, low-energy electron interactions, with a particular focus on dissociative electron attachment (DEA), many model compounds have been investigated over several decades. The majority of these molecules studied possess a cyclic structure, consisting of 5- or 6-membered rings [1]. Therefore, an interesting question emerges: Is there any resemblance among the fragmentation patterns of such compounds and what factors drive the specific fragmentation reactions initiated by DEA? Recently, we studied DEA by comparing a more complex compound (i.e., nicotine). Nicotine is a bicyclic compound containing both 5- and 6-membered rings linked to each other as well as to its two individual compounds (i.e., pyridine and methyl-pyrrolidine) [2]. Nicotine was prone to complex dissociation pathways involving the cleavage of the pyrrolidine ring and isomerization mechanisms. Our results provide important new information about the stability of nicotine and its constituent parts that can further advance our understanding of other ring compounds. Currently, this study is under further systematic investigation for gas phase 5-membered rings (e.g., oxazole, iosoxazole, thiozole), in which positions of hetero atoms vary in their isomers. [1] Gorfinkiel, J.D., Ptasinska, S.; J. Phys B 50 (18), 182001, 2017; [2] Ryszka, M., Alizadeh, E., Li, Z., Ptasinska, S.; J. Chem. Phys. 147 (9), 094303, 2017; [3] Li, Z., Carmichael, I., S. Ptasinska, S.; Phys. Chem. Chem. Phys. 20 (27), 18271, 2018 [Preview Abstract] |
Tuesday, October 29, 2019 2:30PM - 2:45PM |
ET1.00003: Nonlocal complex potential theory of dissociative electron attachment: Inclusion of two vibrational modes Harindranath Ambalampitiya, Ilya Fabrikant Dissociative electron attachment (DEA) process is important for many applications in plasma industry and radiation damage [1]. Theory of DEA to polyatomic molecules often includes a single vibrational mode in the target molecule, with all the other modes being ``frozen". In the local approximation [2] of DEA, the nuclear motion of the intermediate negative-ion state is described by a Schr\"{o}dinger equation with a local complex potential which is an approximation to a non-local energy-dependent complex operator [3]. Previous non-local DEA calculations assumed only one nuclear degree of freedom in the target molecule. In the present paper we extend the non-local theory by inclusion of two or more degrees of freedom in the target molecule. The theory is then applied to DEA to the CF$_3$Cl molecule by inclusion of the C-Cl symmetric stretch and CF$_3$ ``umbrella" modes. The DEA cross section for specific vibrational states and temperature-averaged cross sections are obtained and compared with the previous theoretical results an experiments. $^1$ I. I. Fabrikant \textit {et al.}, Adv. At., Mol.,Opt. Phys. {\bf 66}, 545 (2017). $^2$ D. T. Birtwistle and A. Herzenberg, J. Phys. B: At. Mol. Phys. {\bf 4}, 53 (1971). $^3$ J. N. Bardsley, J. Phys. B: At. Mol. Phys. {\bf 1}, 349 (1968) [Preview Abstract] |
Tuesday, October 29, 2019 2:45PM - 3:00PM |
ET1.00004: Dissociative recombination (DR) and associative ionization (AI) cross section calculations for the NO$^{\mathrm{+}} \quad +$ e \textless ---\textgreater N $+$ O reaction for atmospheric entry modeling Ewa Papajak, Winifred M. Huo, David W. Schwenke, Richard L. Jaffe AI of N $+$ O is the main mechanism that initiates production of free electrons during the entry of a space vehicle into Earth atmosphere. Subsequent electron impact processes, such as excitation and dissociation, lead to excited species that contribute significantly to radiation. While experimental data on total AI cross sections is available, few experiments address the need for the accurate cross sections for metastable atomic states that are important in entry conditions. We present theoretical cross sections and branching ratios for AI calculated for atomic states which are crucial for non-equilibrium radiative heating. In this work, we calculate cross sections of DR, and determine AI cross sections and branching ratios using microscopic reversibility. First, we calculate and analyze state-of-the-art MRCI potential energy curves. Features of these curves, e.g., excited states of the neutral that cross the ion curve, location of avoided crossings, and the types of atomic states connected to the molecular states, determine the DR mechanism. Secondly, R-matrix calculations provide resonance widths for the electron-scattering. Thirdly, we use the potential curves along with the e-scattering data to carry out the time-dependent wave packet calculations to describe the nuclear motion of the molecular ion upon its collision with an electron. Based on the state distributions profiles in time, these calculations provide cross sections for DR including recombination into high energy atomic states. [Preview Abstract] |
Tuesday, October 29, 2019 3:00PM - 3:15PM |
ET1.00005: A machine learning based model for predicting molecular ionization cross sections Linlin Zhong The electron-impact ionization of molecules is one of the most fundamental collision processes in plasma physics as well as in many areas of application. The electron-impact ionization cross section of a molecule is the key parameter of describing electron-molecule collision ionization. Since obtaining ionization cross sections through experiments is very expensive in most cases, many efforts have been devoted to their theoretical determination. However, the theoretical calculation of molecular ionization cross sections requires the \textit{ab initio} computation which is time-consuming especially for large molecules. Recently, we propose a data-driven model based on machine learning to fast predict molecular ionization cross sections. This model is learned from the data of the small molecules which have less constituent atoms than the large molecule we study. Any machine learning algorithms, such as support vector machine (SVM), can be used to train the model. Our tests indicate that this machine learning based model can generate well-agreed ionization cross sections of molecules and has good generalization performance. [Preview Abstract] |
Tuesday, October 29, 2019 3:15PM - 3:45PM |
ET1.00006: The Interaction of Chiral Electrons with Chiral Molecules and Chiral Surfaces -- A Progress Report Invited Speaker: T.J. Gay The status of our understanding of the dynamical mechanisms that produce enantiomerically-sensitive cross sections when chiral molecules scatter longitudinally-polarized (chiral) electrons in the gas phase will be reviewed. These mechanisms can be classified roughly as (a) Mott scattering, (b) exchange effects due to the target molecule's electron helicity density, and (c) spin-other-orbit coupling. The distinct physics and chemistry of these three mechanisms can be applied to a variety of collision channels including quasi-elastic scattering and dissociative electron attachment. Our latest quasi-elastic scattering data with halocamphor targets will be presented [1], and some new theoretical developments from the S\~{a}o Paulo group will be discussed. The role that these mechanisms play in enantiomeric specificity in the adsorption of chiral molecules on magnetic surfaces will be considered as well [2]. [1] J.M.Dreiling \textit{et al}., J.Phys.B \textbf{51}, 21LT01 (2018) [2] K. Banerjee-Ghosh \textit{et al}., Science \textbf{360}, 1331 (2018) [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700