Bulletin of the American Physical Society
73rd Annual Gaseous Electronics Virtual Conference
Volume 65, Number 10
Monday–Friday, October 5–9, 2020; Time Zone: Central Daylight Time, USA.
Session FT1: Electron Collisions With Atoms and MoleculesLive
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Chair: Alisher Kadyrov, Curtin |
Tuesday, October 6, 2020 8:00AM - 8:30AM Live |
FT1.00001: Electronic excitation cross sections in low energy electron scattering from polyatomic molecules Invited Speaker: Jimena Gorfinkiel State-of-the-art software, based on the use of the R-matrix method and designed to model the interaction of low energy electrons and positrons with polyatomic molecules as well as photoionization, can be used to determine quantitatively accurate electron excitation cross sections for small and mid-size molecules below the ionization threshold. In my talk, I will describe how recent developments of UKRmol$+$ software suite (CPC \textbf{249} (2020) 107092, https://www.ukamor.com/{\#}/software) have enabled highly accurate studies for small targets, the study of bigger targets than ever before and the investigation of the effect of the environment by means of small molecular clusters. I will show examples of the use of the UKRmol$+$ suite to study scattering from BeH$_{\mathrm{2}}$ (PRA \textbf{101} (2020) 052709), pyrimidine (JCP \textbf{144} (2016) 024302) for which agreement with electron energy loss spectroscopy results is excellent, and other targets. I will also discuss other processes that can be investigated with the same approach. [Preview Abstract] |
Tuesday, October 6, 2020 8:30AM - 8:45AM Live |
FT1.00002: Vibronic close-coupling calculations of e-H$_2$ scattering Liam Scarlett, Dmitry Fursa, Igor Bray Theoretical studies of electron-molecule collisions are inherently more complicated than electron-atom collisions because of the extra degrees of freedom related to nuclear motion. Close-coupling methods have been shown to be ideal for modeling all scattering processes over wide ranges of incident energies, but the large number of additional reaction channels due to the rovibrational target structure has made close-coupling calculations for molecular scattering systems unfeasible without the use of approximations. Previous calculations performed using vibrational close-coupling techniques have utilized approximate polarisation potentials to account for coupling to excited electronic states, thereby restricting them to studies of electronically-elastic vibrational excitation. Methods which have explicitly included coupling between electronic states, such as molecular convergent close-coupling (MCCC) or $R$-matrix, have relied on the adiabatic-nuclei approximation to decouple the electronic and nuclear motions. The MCCC method has now been extended to explicitly account for the coupling between electronic and vibrational target states using a vibronic close-coupling approach. In this talk we detail the new development and present results for electrons scattering on H$_2$. [Preview Abstract] |
Tuesday, October 6, 2020 8:45AM - 9:00AM Live |
FT1.00003: Dissociative electron attachment studies of molecules containing amide bond Dipayan Chakraborty, Lauren Eckermann, Ian Carmichael, Sylwia Ptasinska Dissociative electron attachment (DEA) to biomolecules plays an important role in understanding radiation damage to biological targets initiated by high-energy radiation. The DEA studies on biological systems containing the amide bond provide the necessary information to understand their fragmentation [1-2]. Our recent study revealed that the dissociation of the amide bond in the DEA process can proceed through the core-excited Feshbach resonance, where the resonant electron capture occurred into one of the metastable valance states of the molecule. However, the resonant states' characterisation is not possible due to the complex nature of the molecules. In the present context, we focus on smaller molecules containing amide bonds, that can be considered models for larger biologically relevant molecules, i.e. peptides. Here, we present our recent experimental and computational studies of gas-phase DEA to N-ethylformamide and N-ethylacetamide molecule. The location of different resonant states and their corresponding dissociation channels are identified. With the help of quantum chemistry calculations, threshold energies of each dissociation channels are calculated. [1] J. D. Gorfinkiel and S. Ptasinska, \textit{J. Phys. B: At. Mol. Opt. Phys.,} 2017, 50, 182001. [2] Z. Li, M. Ryszka, M. M. Dawley, I. Carmichael, K. B. Bravaya and S. Ptasinska, \textit{Phys. Rev. Lett.,} 2019, 122, 073002. [Preview Abstract] |
Tuesday, October 6, 2020 9:00AM - 9:30AM Live |
FT1.00004: Complete collision data set for electron scattering from molecular hydrogen and its isotopologues Invited Speaker: Dmitry Fursa Cross sections resolved in the rovibrational levels of the target are required for determining the properties and dynamics of many low-temperature plasmas. We have applied the Molecular Convergent Close-Coupling (MCCC) method to produce a comprehensive set of vibrationally-resolved cross sections for electron collisions with molecular hydrogen and its isotopologues comprised of more than 57,000 entries [1]. This complete collision data set is available to the research community via the LXCat database and the dedicated MCCC database (mccc-db.org). For H$_2$ the data set includes transitions from all 14 vibrational levels of the ground electronic state to all vibrational levels of 18 excited electronic states (all states in the $n=2,3$ shells). Examples of modeling calculations based on the MCCC dataset will be presented for collisional-radiative (CR) modelling and Monte-Carlo simulation of electron propagation in H$_2$ plasmas. A study of electron scattering from the metastable $c~^3\Pi_u(v=0)$ state of H$_2$ will be presented and progress towards establishing a comprehensive dataset of vibrationally-resolved cross sections for transitions between excited levels will be discussed. [1] Scarlett et al., Atom. Data. Nucl. Data Tables (2020), submitted. Coauthors: L.~H.~Scarlett, I.~Bray, M.~C.~Zammit, Yu.~Ralchenko. [Preview Abstract] |
Tuesday, October 6, 2020 9:30AM - 9:45AM |
FT1.00005: Scattering of electrons with perfluoroketone molecules Chetan Limbachiya, Nirav Thakkar, Mohit Swadia, Minaxi Vinodkumar, Nigel Mason Per?uoroketone (PFK) molecules have been determined to have extremely low global warming potentials (GWPs) and therefore may have applications in next generation gas discharges and plasma reactors [Kesari et al, Patent no. US 6540930B2 (2003)] and can replace SF$_{\mathrm{6}}$ for various applications. In this work elastic and inelastic cross sections for electron scattering from per?uoroketone (PFK) molecules, C$_{\mathrm{x}}$F$_{\mathrm{2x}}$O (x $=$ 1-6) are reported from the ionization potential to 5 keV using the Spherical Complex Optical Potential formalism [1]. The ionisation cross sections are are derived using the Complex Scattering Potential-ionization contribution (CSP-ic) method and are found in good agreement with previous data. We also describe low energy calculations (below 15 eV) using the ab-initio R-matrix [2] to evaluate resonances, differential and total cross sections. [1] Swadia M, Thakar Y, Vinodkumar M, Limbachiya C., The European Physical Journal D~\textbf{71}(4) (2017) 85 [2] Limbachiya C, Vinodkumar M, Mason N., Physical Review A. \textbf{83 (}2011) 042708 . [Preview Abstract] |
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