Bulletin of the American Physical Society
85th Annual Meeting of the APS Southeastern Section
Volume 63, Number 19
Thursday–Saturday, November 8–10, 2018; Holiday Inn at World’s Fair Park, Knoxville, Tennessee
Session A01: Atomic, Molecular, and Optical Physics |
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Chair: John Yukich, Davidson College Room: Holiday Inn Knoxville Downtown Summit |
Thursday, November 8, 2018 8:30AM - 9:00AM |
A01.00001: Atomic and molecular plasma spectroscopy in the laboratory for interpretation of astrophysical white dwarf star signatures Invited Speaker: Christian G Parigger This work discusses atomic and molecular spectroscopy of laboratory laser plasma and analysis of selected star spectra. Time-resolved atomic hydrogen line-of-sight measurements yield electron density and excitation temperature. Equally, selected diatomic molecular recombination spectra are measured to infer excitation temperature following optical breakdown in standard ambient temperature and pressure air, and in selected gas mixtures. The recorded and fitted experimental data are compared with available absorption spectra from selected white dwarf stars. Spectral signatures are presented from alpha canis majoris B and alpha canis minoris B, or Sirius B and Procyon B, respectively, and from other selected white dwarfs. Applications of atomic hydrogen and diatomic molecular diagnostics are of interest, including reconciliation of hydrogen Balmer alpha and beta time-resolved plasma-line profiles and red-shifts with white-dwarf, gravitational red-shifts and details of hydrogen absorption profiles. Selected astrophysical white dwarfs reveal equivalent widths that are typically one order of magnitude larger than those for the sun. Current research efforts in laboratory plasma physics extend to studies of hyper-sonic expansion dynamics subsequent to laser-induced breakdown, determination of electron densities and atomic and molecular species distributions, atomic spectral line shapes, and molecular band appearances. These topics are also contents of current astrophysical research, including interpretation of measured white-dwarf absorption profiles and modeling of atmosphere compositions. |
Thursday, November 8, 2018 9:00AM - 9:30AM |
A01.00002: Towards quantum sensing with noble-gas-trapped thulium atoms Invited Speaker: Colin V Parker Motivated by the prospect of atomic-scale sensing, we investigate the properties of thulium atoms trapped in solid helium and argon matrices. Neutral thulium (Tm) is a lanthanide atom whose single-hole f-shell electronic structure is equivalent to that in the Yb3+ ion frequently used in solid-state optical applications. Existing spectroscopy in solid helium [1] suggests that Tm metastable lifetimes can remain long, and that the linewidth can become quite narrow on inner-shell f-f transitions. Potential placement of noble gas films on material or device surfaces would allow sensing of the local environment, and the relatively unperturbed nature of the transitions suggests a high degree of quantum control may be possible. If these attributes carry over to neon and argon hosts this would be desirable because solid helium exists only under pressure at very low temperatures. However, the nature of the perturbations (such as crystal field splitting) due to these noble gas hosts are unknown. As a first step towards understanding them we will present lifetime and coarse lineshape measurements of the 1140 nm line in both neon and argon hosts. In both cases lifetimes are tens of milliseconds. Spectroscopy shows most of the fluorescence signal within the 3 nm spectrometer resolution, with a possible weak satellite feature in argon.
[1] Ishikawa et al, PRB 56 780 (1997) |
Thursday, November 8, 2018 9:30AM - 10:00AM |
A01.00003: Optical control of electron emission at the attosecond timescale Invited Speaker: Guillaume Marc Laurent Coherent control of electron dynamics in matter is a growing research field in ultrafast science, which has been mainly driven over the last two decades by major advances in laser technology. Recently, the advent of extreme-ultraviolet (EUV) light pulses in the attosecond time scale (1as = 10-18s) has opened up new avenues for experimentalists to manipulate the electronic dynamics with unprecedented precision. In this work, we demonstrate that an asymmetric electron emission from atomic targets can be generated and controlled by combining an attosecond pulse train (APT) and a weak IR field (1011 W/cm2). Electron wave-packets are formed by ionizing argon gas with such APT in the presence of the IR field. Consequently, a mix of energy-degenerate even and odd parity states is fed into the continuum by one- and two-photon transitions. These interfere, leading to an asymmetric electron emission along the polarization vector. At some appropriate time delay between the APT and IR fields, the even and odd angular continuum wave function resulting from one- and two-photon transitions, respectively, add constructively on one side (up) of the polarization vector direction and destructively on the other side (down), thus creating a strong up-down asymmetry in the angular emission of the photoelectrons. The direction of the emission can be controlled by varying the time delay between the two pulses. |
Thursday, November 8, 2018 10:00AM - 10:30AM |
A01.00004: Catalysis of Stark-tuned interactions between ultracold Rydberg atoms Invited Speaker: C. I. Sukenik When highly excited atoms (known as Rydberg atoms) collide, they may change their quantum state if the total electronic energy of the two atoms before and after the collision is about the same. This process can be made resonant by tuning the energy levels of the atoms with an electric field (the Stark shift) so that the energy difference between incoming and outgoing channels vanishes. This condition is known as a “Forster resonance.” We have studied a particular Forster resonance in rubidium: 34p + 34p --> 34s + 35s, by investigating the time dependence of the state change in an ultracold environment. Furthermore, we have added 34d state atoms to the mix and observed an enhancement of 34s atom production. We attribute this enhancement to a catalysis effect whereby the 34d atoms alter the spatial distribution of 34p atoms that participate in the energy transfer interaction. In this talk, we will review the properties of ultracold Rydberg atoms, present results from the catalysis experiment, discuss insights gained from model calculations and comment on future plans for this line of research. |
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