Bulletin of the American Physical Society
86th Annual Meeting of the APS Southeastern Section
Volume 64, Number 19
Thursday–Saturday, November 7–9, 2019; Wrightsville Beach, North Carolina
Session B03: Atomic, Molecular and Optical Physics I |
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Chair: John Yukich, Davidson College Room: Holiday Inn Resort Turtlewatch |
Thursday, November 7, 2019 11:00AM - 11:30AM |
B03.00001: Atoms and Molecules Illuminated from Within Invited Speaker: Allen Landers Molecules in the gas phase are unique quantum systems in that they exhibit many fundamental quantum mechanical effects and are yet complex enough to challenge the most rigorous theoretical treatments. Exploring these quantum systems in detail is challenging in large part because molecules in the gas phase are randomly oriented as molecules tumble and translate through space. I will describe a series of experiments that allows us to study electronic and fragmentation dynamics in the molecular frame, enabling observation of collective quantum phenomena in the gas phase. In particular, I will show how a resonant electron wave propagates through a molecular potential, interrogating the molecule as it emerges from one of the core molecular orbits, and how simultaneously measuring multiple particles allows for a “complete” determination of the continuum quantum states of an isolated molecule. [Preview Abstract] |
Thursday, November 7, 2019 11:30AM - 12:00PM |
B03.00002: TES based x-ray spectroscopy at the NIST EBIT Invited Speaker: Endre Takacs A broad-band, high energy-resolution x-ray microcalorimeter has recently been installed on the electron beam ion trap (EBIT) of the National Institute of Standards and Technology (NIST). The transition-edge-sensor based instrument covers photon energies between 300 eV to 15 keV and provides an energy resolution of around 4 eV across this range. The new, state-of-the-art NIST EBIT X-ray Transition-edge-sensor (NEXT) spectrometer is built upon 192 sub-kelvin detector elements, which have both high spectral resolution and high collection efficiencies. These characteristics make NEXT a powerful tool for x-ray spectroscopy of highly charged ions due to the low photon flux inherent to the EBIT. The first measurements with NEXT allowed us to record and identify dozens of spectral lines from up to about 70 times ionized heavy elements. Radiative transitions in these ions can be calculated with high theoretical precision, therefore the NEXT data provide unique benchmarks for testing~the most sophisticated atomic theories including relativistic and quantum electrodynamics contributions in multi-electron highly-charged and highly-excited ions. The first experimental results will be presented and compared with a large-sale collisional radiative model of the EBIT plasma emission. The capabilities of the new instrument will be addressed showing that it is ideally suited for high x-ray energy resolution studies of static and transient highly charged ion plasmas. [Preview Abstract] |
Thursday, November 7, 2019 12:00PM - 12:12PM |
B03.00003: Control of the Photoemission Process at the Attosecond Time-Scale Brady Unzicker, Spenser Burrows, Bree Tatum, John Vaughan, Trevor Hart, Davis Arthur, Guillaume Laurent The generation of high-harmonics of an intense IR field is a nonlinear process capable of producing attosecond pulses comprised of a comb of odd-harmonics reaching into the extreme ultraviolet (XUV). By adding a low-intensity second harmonic to the fundamental infrared driving field, both odd and even harmonics of the fundamental field can be generated, which in turn leads to the generation of attosecond pulses with tunable temporal profiles. In this work, we have employed such a tunability to control the photoemission process from atoms. Attosecond pulses with well-defined temporal profiles were used to ionize an atomic target in the presence of an IR field. An asymmetric electron emission resulting from the interference between one- and two-photon quantum transitions is produced. By controlling the intensity ratio and phase delay between the fundamental field and its second harmonic, we show that the direction of emitted photoelectrons can be varied along the polarization axis of the driving field. [Preview Abstract] |
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