Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session N09: Atomic and Molecular Databases and Data Applications |
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Chair: Yuri Ralchenko, NIST Room: Wisconsin Center 103DE |
Thursday, May 30, 2019 8:00AM - 8:30AM |
N09.00001: Progress in Quantitative Atomic Spectroscopy and the Connection to Astrophysics Invited Speaker: James Lawler Atomic spectroscopy played a central role in the development of quantum mechanics and modern physics. This historical significance may motivate continued teaching of the field, but atomic spectroscopy has lasting significance through its applications in astrophysics. Most of the detailed physical and chemical knowledge humans have now, or may ever learn, about the Universe outside our solar system is from spectroscopy. Databases of atomic and molecular spectroscopic information play an important role in astrophysical research. The origins of the non-primordial elements are an example of a long term research problem in astrophysics that is critically dependent on atomic spectroscopy. Non-primordial here refers to almost the entire periodic table except for H and He produced in the Big Bang. Broadly tunable organic dye lasers created many opportunities to improve spectroscopic parameters including energy levels, wavelengths, and hyperfine structure for atoms and ions. Such data are of value but reasonably accurate atomic transition probabilities are critical to exploring the production of non-primordial elements. The above mentioned organic dye lasers, in combination with a simple and robust atom/ion beam source made radiative lifetime measurements routine for atoms and ions throughout the periodic table. Radiative lifetimes combined with emission branching fractions yield accurate absolute atomic transition probabilities essential for the analysis of stellar spectra. The synthesis of all elements beyond the Fe-group is through n(eutron)-capture because fusion reactions become endothermic beyond the Fe-group. Half of these heavy isotopes are made via s(low)-process n-capture which occurs in AGB stars. The other half are made via r(apid)-process n-capture which occurs in extremely violent events that produce high densities of free neutrons. Recent studies of a binary n(eutron)-star merger first detected by LIGO and FERMI-LAT and observed in great detail by many ground and space based observatories confirmed that n-star mergers do produce r-process n-capture isotopes. There are still many unanswered questions about r-process n-capture sites and about the chemical evolution of the Universe. The role of atomic spectroscopy in studies of the r-process n-capture nucleo-synthesis will be discussed. [Preview Abstract] |
Thursday, May 30, 2019 8:30AM - 9:00AM |
N09.00002: Spectroscopy meets data science to aid planetary remote sensing: the HITRAN and HITEMP databases Invited Speaker: Iouli Gordon The HITRAN spectroscopic database is a backbone of the interpretation of terrestrial and planetary atmospheric retrievals and is an important input to the radiative transfer codes. Apart from atmospheric applications HITRAN is being used in medicine, astrophysics, air-quality monitoring, instrument calibration and many other areas of science and industry. The database is serving the scientific community for nearly half-a-century with every new edition being released every four years. The extent of the updates from edition to edition ranges from updating a few lines of certain molecules to complete replacements of the lists and introduction of additional isotopologues. The most recent release of the database is HITRAN2016 [1]. It consists of line-by-line lists, experimental absorption cross-sections, collision-induced absorption data and aerosol indices of refraction.\\ \\ Taking advantage of the new structure and interface available at www.hitran.org [2] and the HITRAN Application Programming Interface [3] the amount of parameters has also been significantly increased, now incorporating, for instance, non-Voigt line profiles; broadening by gases other than air and “self”; and other phenomena, including line mixing.\\ \\ References [1] I.E. Gordon et al, JQSRT 203, 3 (2017). [2] C. Hill et al, JQSRT 177, 4 (2016). [3] R.V. Kochanov et al, JQSRT 177, 15 (2016)\\ \\ In collaboration with: Laurence S. Rothman, Robert Hargreaves, Yan Tan, Roman V. Kochanov, Christian Hill [Preview Abstract] |
Thursday, May 30, 2019 9:00AM - 9:30AM |
N09.00003: Electron Collisions with Atoms and Ions: Current Status and Future Prospects Invited Speaker: Klaus Bartschat Accurate data for electron collisions with atoms and ions are required for many modelling applications in a variety of fields, including astrophysics, atmospheric physics, as well as plasma physics over a wide range of electron temperatures [1]. Since it is virtually impossible to measure all the data needed for state-of-the-art collisional radiative models (CRMs), much of the responsibility for generating sufficiently comprehensive datasets has been put on theory. Consequently, a variety of methods have been developed and applied since the early days of quantum mechanics [2]. They include special-purpose approaches that are suitable but also limited to particular processes (e.g., elastic scattering), perturbative techniques (e.g., first- and second-order plane-wave or distorted-wave methods, which are usually limited to sufficiently high energies), and the non-perturbative close-coupling (CC) approach that is based on an (in principle complete) expansion of the projectile + target scattering wave function. CC methods were originally designed for low energies and near-threshold resonances, but the inclusion of so-called ``pseudo-states'' has extended the regime of applicability tremendously, even enabling the calculation of ionization cross sections. While the problem for electron collisions with light (quasi-)one- and (quasi-)two-electron targets (H, He, light alkalis and alkaline-earth elements, and the corresponding iso-electronic ions) is considered to be essentially solved, this is by no means the case for heavy, complex, open-shell targets. Examples include Fe and its lowly charged ions, which are of tremendous importance for astrophysics, the heavy noble gases (Ne$-$Xe) for modelling of various plasmas, and targets like W and its ions where data are needed to model fusion reactors. In this talk, I will introduce the basic ideas behind a selection of methods, discuss their strengths and weaknesses, and concentrate on how to assess the quality of the data [3] that are available from a number of databases maintained worldwide. [1] K. Bartschat, Journal of Physics B {\bf 51} (2018) 132001. [2] K. Bartschat, J. Tennyson, and O. Zatsarinny, Plasma Processes and Polymers {\bf 49} (2017) 1600093. [3] H.K. Chung {\it et al.}, Journal of Physics D {\bf 49} (2016) 363002. [Preview Abstract] |
Thursday, May 30, 2019 9:30AM - 10:00AM |
N09.00004: NIST's atomic databases for applied and fundamental science Invited Speaker: Alexander Kramida NIST maintains several databases on atomic properties. This talk will give a brief review of these databases with focus on the Atomic Spectra Database (ASD), which is the only source of critically evaluated data on atomic energy levels, spectral lines, and transition probabilities. These data are widely used for plasma modeling in astrophysics, fusion science, and many other diverse fields from environmental science to nuclear physics and atomic clocks. A recently released new online interface was designed for modeling of laser induced breakdown plasmas used in analysis of composition of materials, such as minerals, steel alloys, glasses, and even Mars rocks. All these applications demand further extension and better precision of atomic data sets, which requires new extensive compilations and in many cases new research. These requirements that will be discussed in the talk demand a change in current culture of atomic physics research worldwide. \\ \\ In collaboration with: Joseph Reader, Gillian Nave, Karen Olsen, and Yuri Ralchenko. [Preview Abstract] |
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