Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X05: Structure and Properties of Atoms, Ions, and MoleculesLive
|
Hide Abstracts |
Chair: Z.T. Lu, USTC |
Friday, June 4, 2021 8:00AM - 8:12AM Live |
X05.00001: An improved measurement of the ground state tensor polarizability of Cesium atoms Teng Zhang, Zhenyu Wei, David S. S Weiss We will describe a direct measurement of the ground state tensor polarizability (GSTP) of Cs using laser cooled atoms trapped in optical lattices. Precision measurement of the Cs GSTP provides a way to test third order atomic calculations, which are important for determining the weak charge from atomic parity violation measurements. We measure the GSTP by simultaneously driving transitions in two pairs of magnetic sublevels and measuring the populations in individual magnetic sublevels. This is the first GSTP measurement of the F=3 hyperfine level. Our measurement is consistent with existing experimental and theoretical results for the F=4 hyperfine level, but its <10-3 relative precision is approximately two orders of magnitude more precise than previous experiments or existing theory. |
Friday, June 4, 2021 8:12AM - 8:24AM Live |
X05.00002: Magic Wavelengths of the Yb 6s2 1S0 - 6s6p 3P1 Intercombination Transition Tao Zheng, Yang Yang, Marianna S Safronova, Ulyana I Safronova, Zhuan-Xian Xiong, Tian Xia, Zheng-Tian Lu We calculate and measure the magic wavelengths for the the narrow 6s2 1S0 - 6s6p 3P1 intercombination transition of the neutral ytterbium atom. The calculation is performed with the ab initio configuration interaction (CI) + all-order method. The measurement is done with laser spectroscopy on cold atoms in an optical dipole trap. The magic wavelengths are determined to be 1035.68(4) nm for the π transition (∆m= 0) and 1036.12(3) nm for the σ transitions (|∆m|= 1) in agreement with the calculated values. Laser cooling on the narrow intercombination transition could achieve better results for atoms in an optical dipole trap when the trap wavelength is tuned to near the magic wavelength. |
Friday, June 4, 2021 8:24AM - 8:36AM Live |
X05.00003: Power-Law Distribution of Line Intensity in Complex Many-Electron Atoms Keisuke Fujii, Julian C Berengut It has long been known that the number of weak lines from many-electron atoms follows a power-law distribution of intensity. This property has been observed by both experiments and computer simulations for several atomic systems. However, its origin has not yet been clarified. Here we report that the combination of two statistical models ---an exponential increase in the level density of many-electron atoms and local thermal equilibrium of the excited state population--- produces a surprisingly simple analytical explanation for this power-law dependence. We find that the exponent of the power-law is proportional to the electron temperature. This dependence may provide a useful diagnostic tool to extract the temperature of plasmas of complex atoms without line assignments. |
Friday, June 4, 2021 8:36AM - 8:48AM Live |
X05.00004: Structural Properties of Small Bosonic Helium Clusters J Alexander O Yates, D. Blume We use Monte Carlo techniques to investigate the universal behavior of bosonic 4HeN clusters with N = 2 to 10 4He atoms. We determine the energies of these clusters for different realistic He-He potentials. In addition, we consider a potential energy surface that contains attractive two-body Gaussian interactions and repulsive three-body Gaussian interactions whose parameters are adjusted so as to reproduce the two- and three-body energies of the realistic potentials. In agreement with earlier work, we find that the energies of the helium clusters depend rather weakly on the underlying potential model. In addition to the energies, we analyze structural quantities such as the pair distribution function and the radial density. We quantify the dependence on the underlying potential of these quantities. To explore the universal behavior of these small quantum droplets further, the two-body scattering length is “artificially” tuned to the unitary point. |
Friday, June 4, 2021 8:48AM - 9:00AM Live |
X05.00005: Improved accuracy of Compton profiles obtained from the Compton peak region of full spectrum S-Matrix photon scattering doubly differential cross sections. Larry A LaJohn A full Compton photon scattering doubly differential cross section (DDCS) spectrum consists of a Compton peak, an infrared rise and resonances, the later occurring beyond the K-shell. The S-matrix code of Bergstrom et. al. provides such spectra for all atomic subshells. A nonrelativistic expression DDCS=KJ where K is a kinematic factor and J is the Compton profile (CP) is often used to obtain CP from a DDCS spectrum. However this expression is not valid for high photon energies and for the inner and middle shells of moderate to heavy atoms. Here one must use an expression based on the relativistic impulse approximation (RIA). In order to obtain a CP from a DDCS spectrum such an expression must be further approximated so that it is in a DDCS=KJ form. Unfortunately such an expression to be called RKJ becomes progressively less valid with increasing ejected electron binding energy Eb increasing orbital angular momentum quantum number (l) and increasing photon scattering angle θ. In the present work it is demonstrated that a corrected RKJ expression can yield an accurate CP from the Compton peak region of a full DDCS spectrum even for the inner and middle shells of heavy atoms where the RKJ error is greatest. |
Friday, June 4, 2021 9:00AM - 9:12AM Live |
X05.00006: All Masses and Mass Groups Have Recently Been Found To Exhibit No Motion.Linear, Rotation, and Vibration Singly Or In Some Combination.Thus, Many Past And Future Physics Equations Must Include These Factors To Insure Their Correctness As Einsteins Equation ForTotal Energy of Masses At Slow Speeds. Stewart E Brekke Every Mass or Mass Group, when created, exhibit when created, no motion, Linear, Rotational and/or Vibratory Motion, Singly or in some Combination, due to excess energy in creation which may be modified by external forces--A Natural Law. In 1905 Einstein derived the total energy at slow speeds of a mass was E = mc2 + 1/2m2 |
Friday, June 4, 2021 9:12AM - 9:24AM Live |
X05.00007: The structure of a photon, a new atom which is the primary building block of all matter Gh. Saleh, M. J. Faraji The universe contains organized structures on all different scales, from small systems like the atom, to galaxies, and extremely large structures that contain billions of galaxies. If we look at the sky, we see the planets rotate around the Sun which has its rotation in the galaxy; as well as galaxies have their own axis to turn around. Thus, observing from the sky to the atom, we see an identical structure that is about a rotation around a central axis; a structure similar to that of the atom which has a nucleus and electrons rotating around. |
Friday, June 4, 2021 9:24AM - 9:36AM Live |
X05.00008: A Multi-Center Quadrature Scheme for the Molecular Continuum Heman Gharibnejad, Nicolas Douguet, Barry I Schneider, Jeppe Olsen, Luca Argenti Computing electronic integrals for polyatomic molecules is a numerical challenge. Becke's partitioning scheme is a possible solution that works well for integrands that fall off rapidly at large distances. When applied to states in the electronic continuum, however, Becke's scheme converges slowly and may be expensive. We present a modified version of Becke's scheme that is applicable to functions in the electronic continuum, such as those involved in molecular photoionization and electron–molecule scattering, which ensure convergence and efficiency. In the new scheme, Becke's atomic weights are smoothly switched off within a range of few bond lengths from their respective nuclei, and complemented by an asymptotically unitary weight. The integrals are evaluated on small spherical grids, centered on each atom, with size commensurate to the support of the corresponding atomic weight. The integral of the interstitial and long-range region is evaluated with a central grid. We demonstrate that the method provides high accuracy for a wide range of integrals and has good scaling properties for the evaluation of the hybrid bi-electronic integrals needed in photoionization and electron-scattering studies. |
Friday, June 4, 2021 9:36AM - 9:48AM Live |
X05.00009: Determination of Cooper minima and shape resonances of nS and nD Rydberg states in Rb and Cs Eric G Paradis, Michael A Viray, Georg A Raithel Rydberg atoms generally become less sensitive to photoionization (PI) as the photon energy increases due to an increasing mismatch between bound-state and free-electron wavefunctions. However, in certain PI channels this trend is interrupted by pronounced minima in the PI cross sections. Here we present calculations of the PI cross sections in both rubidium and cesium Rydberg atoms over a wavelength range from the infrared to the ultraviolet, using model potentials from [M. Marinescu, H. R. Sadeghpour, and A. Dalgarno, Phys. Rev. A 49, 982 (1994)]. The resulting cross sections exhibit both broad PI minima in the nS to ϵP PI channels of both Rb and Cs (with free-electron energy ϵ) identified as Cooper minima, and much narrower features in the nD to ϵF channels due to shape resonances of the free-electron states. The small total PI cross sections of these states make them ideal for applications of optically excitable laser-trapped Rydberg atoms. Examples of applications include quantum simulation, quantum information processing and high-precision spectroscopy. |
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