Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session Q06: Collisions in Atomic and Molecular Systems |
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Chair: Allison Harris, Illinois State University Room: 206 A |
Thursday, June 8, 2023 8:00AM - 8:12AM |
Q06.00001: C60 Resonant Charge Transfer Through the Temporary Formation of Carbon Bonds Jonathan C Smucker, John A Montgomery, Jr., Robin Cote, Vasili Kharchenko Charge transfer has been a well-studied subject for years due to its various applications to plasma physics, astrophysics, atmospheric sciences and other branches of physics and chemistry. Charge transfer is often used as a way of probing fundamental quantum mechanics as the dynamics of electrons is of crucial importance to these reactions. However, when charge transfer is studied with more complex targets, such as large molecules, charge transfer can be used to probe chemical reactions that are vital to properly understanding these collisions. We present our model on a new type of charge transfer between C60 and its cation. Molecular dynamic simulations have shown that when these two large molecules collide, they temporarily bond forming a “dumbbell shaped” C120 molecule. This temporary “bridge” extends the interaction time between the molecules increasing the charge transfer cross section. We compare our model to previously measured experimental data and find good agreement. To our knowledge this is the first theoretical model to predict large scattering angle C60 resonant cross sections. |
Thursday, June 8, 2023 8:12AM - 8:24AM Withdrawn |
Q06.00002: Magnetic-dipole transitions in highly charged Co-like ions to study the QED and higher order effects in EBITs Roshani Silwal, Samuel C Sanders, FNU Dipti, Adam Hosier, Yuri Ralchenko, Endre Takacs Atomic theory is complicated for many-body systems where proper treatment of the correlation effects can be challenging. As correlation decreases rapidly with Z, highly charged ions offer test grounds to benchmark modern atomic theories. These ions also have enhanced relativistic and quantum electrodynamics (QED) effects and can be easily created with Electron Beam Ion Traps (EBIT). Recently highly accurate tests of Breit and QED effects on systems with suppressed correlations and enhanced relativistic effects, labeled as “Layzer-quenched” systems [1] have been proposed and studied [2,3]. We present direct measurements of the 3d9 2D3/2 → 2D5/2 fine structure of Co-like Yb, Re, Os, and Ir with the National Institute of Standards and Technology EBIT facility. Comparisons with the existing theories [4-5] are made in an effort to understand the Breit interaction and the self-energy contribution to QED effects. |
Thursday, June 8, 2023 8:24AM - 8:36AM |
Q06.00003: Controlling Quantum Systems with Modulated Electron Beams Philipp Haslinger, Matthias Kolb, Thomas Weigner, Thomas Spielauer, Dennis Rätzel, Giovanni Boero Coherent manipulation of quantum systems with precisely controlled electromagnetic fields is one of the key elements of quantum optics and quantum technologies. Here, I will give an overview of our recent work [1], which theoretically demonstrates that the non-radiative electromagnetic near-field of a temporally modulated free-space electron beam can be utilized for coherent control (even on the nanoscale e.g. in an electron microscope) of quantum systems. I show that such manipulation can be performed with only classical control over the electron beam itself and that potential challenges like shot noise and decoherence through back action on the electrons are for certain parameter ranges insignificant for our approach. I will present possible experimental realizations using laser cooled, state-selected potassium atoms or unpaired electron spins in a solid state sample such as BDPA and point out interesting applications for example painted potentials, which could be realized using a spatially modulated electron beam. |
Thursday, June 8, 2023 8:36AM - 8:48AM |
Q06.00004: Uniform treatment of direct and indirect mechanisms in low-energy dissociative recombination of CF+ and CH+ Joshua B Forer, David Hvizdos, Xianwu JIANG, Chris H Greene, Jeoffrey Boffelli, Ioan Schneider, J. Zs. Mezei, MEHDI Ayouz, Viatcheslav Kokoouline The dissociative recombination (DR) of molecular ions is an important process in several molecular plasmas, such as for plasma-based technologies and tracking the evolution of interstellar clouds. Calculating DR cross sections, needed to determine DR rate coefficients to understand the evolutions of such molecular plasmas, often becomes difficult when the direct and indirect DR mechanisms are simultaneously important. This typically occurs in ions with low-energy electronic resonances, e.g., open-shell molecular ions. The present theoretical method treats the direct and indirect mechanisms uniformly in the case of a diatomic ion, with or without low-energy electronic resonances, while resolving electronic, vibrational, and rotational degrees of freedom, and can likely be scaled to study the DR of triatomic ions. Our method is based on R-matrix scattering calculations, performed at several internuclear distances, rovibrational frame transformation, and multichannel quantum-defect theory. The K-matrices obtained from such scattering calculations do not exhibit electronic Rydberg resonances due to the excited states of the ion, but the physics is contained implicitly in our scattering matrices so that we can more accurately describe the scattering of the electron at low collision energies. The method is easy to implement; it does not require explicit calculation of, e.g., Rydberg-Rydberg couplings or bound dissociative states of the neutral molecule. We apply this approach to the CH+ and CF+ ions and compare our results to experimental measurements from storage-ring experiments. |
Thursday, June 8, 2023 8:48AM - 9:00AM |
Q06.00005: Non-universal quantum dynamics of the ultracold chemical reaction for Li+NaLi(3Σ+) → Li2 (3Σu+)+Na Masato Morita, Brian K Kendrick, Jacek Klos, Svetlana Kotochigova, Paul Brumer, Timur V Tscherbul In a theoretical study of ultracold barrierless chemical reactions between spin-polarized NaLi molecules and Li atoms, we find strong signatures of non-universal reaction dynamics. Specifically, we observe a large sensitivity of the total reaction rate coefficient to small variations in the short-range non-additive three-body potential of the spin-polarized NaLi2 (4A) reaction complex. The sensitivity occurs despite the presence of a deep attractive well in the ab initio PES of the complex. We attribute the origin of this effect to the relatively small number of open reaction channels. In other words, short-range interactions in reaction complexes can be effectively probed via ultracold reactive scattering experiments that measure total reaction rates. |
Thursday, June 8, 2023 9:00AM - 9:12AM |
Q06.00006: Radiative Double-Electron Capture (RDEC) by single-layer graphene incident with F9,8+ ions* Khushi Bhatt, David La Mantia, Shuvo Dutta, Tyler D Ulrich, Uthpalawanna Abesekera, Merlin J Hall, Hansaka S Weerarathne, John A Tanis, Asghar Kayani Radiative double-electron capture (RDEC) takes place when the capture of two electrons by an ion is accompanied by the simultaneous emission of a single photon. This process is considered the inverse of double photoionization by a single photon. RDEC has been successfully studied with F9,8+ ions on gas [1] and thin-foil [2] targets and recently it has been investigated for single-layer graphene [3]. This work is done using the 6-MV tandem van de Graaff accelerator at WMU. A graphene target (∼0.35 nm thick) was mounted on a silicon nitride grid (200 nm thick) consisting of ∼6400 holes of 2 µm diameter on a 200 µm thick substrate. A Si(Li) spectrometer placed at 90° to the beam detected the emitted x rays in coincidence with magnetically separated outgoing charge particles counted with silicon surface-barrier detectors. |
Thursday, June 8, 2023 9:12AM - 9:24AM |
Q06.00007: Minimal model of mobile particles interacting with an infinite one-dimensional lattice: dissipation, thermalization, drag, and diffusion Ben A Olsen, Harshitra Mahalingam, Zhun Wai Yap, Aleksandr Rodin We explore the classical dynamics of mobile particles interacting with an infinite one-dimensional chain of harmonic oscillators (a 1D lattice). This effective model describes ionic conduction in anisotropic solid-state materials or molecular motion in nanotubes. Through a combination of analytic and numerical calculations, we show that, in the absence of thermal motion in the lattice, coupling to the lattice will dissipate the mobile particle's kinetic energy. This dissipation leads to drag that is nonmonotonic in the particle speed. Under a constant bias, this system exhibits multiple steady drift velocities, linking macroscopic transport to microscopic lattice properties. We discuss how thermal motion influences these properties, and how such a model could be implemented in a collection of trapped ions or neutral atoms to explore thermalization and transport in low-dimensional systems. |
Thursday, June 8, 2023 9:24AM - 9:36AM |
Q06.00008: A Gauge Field Theory of Coherent Matter Waves Katarzyna Krzyzanowska, Dana Z Anderson Matter-wave is a concept well-entrenched in physics referring to the quantum-mechanical wave-particle duality, where an individual or an ensemble of particles is characterized by de Broglie wavelength. It is nicely exemplified by the flux of atoms extracted from a Bose-Einstein condensate (BEC), where the de Broglie wavelength of individual particles overlaps creating a macroscopic wavefunction. Amongst various applications, the achievement of BEC catalyzed the field of atomtronics –the atom analog of electronics in which atom flux and chemical potential substitute for electric current and potential. As fundamentally non-thermal-equilibrium open quantum systems, even simple atomtronic circuits prove challenging for many-body methods typically used to describe simple BEC dynamics. |
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