Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session H07: Spectroscopy, Lifetimes, and Oscillator Strengths |
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Chair: Wes Walter, Denison University Room: Grand D |
Wednesday, May 30, 2018 8:00AM - 8:12AM |
H07.00001: Absolute Measurement of Fluorescent Quantum Yield using Photothermal Deflection Spectroscopy Stephen Johnson, Brandon Couch, Andrew Meyer In this talk we will present a new method to measure the fluorescent quantum yield of fluorophores without the need for calibration standards. The method utilizes photothermal deflection spectroscopy -- a technique known for its sensitivity in detecting low-level optical absorptions. Measurement of fluorescent quantum yield is realized through analysis of spectroscopic data, from which the quantum yield can be extracted as a single fitting parameter. This method obviates the need for calibrated reference samples, integrating sphere measurements, or even multiple measurements of the same sample, as an absolute determination of fluorescent quantum efficiency can be achieved in one measurement. [Preview Abstract] |
Wednesday, May 30, 2018 8:12AM - 8:24AM |
H07.00002: Testing quantum electrodynamics in neutral beryllium-9 Eryn Cook, Alisha Vira, Emma Livernois, Carson Patterson, Will Williams We report on measurements for the absolute transition frequency and hyperfine constants for the 2s2p 1P1 state in neutral beryllium-9. The absolute transition frequency, when compared to a theoretical prediction[1], serves as a test of quantum electrodynamics. Progress on spectroscopy to determine the absolute frequency and hyperfine structure for the 2s3d 1D2 state and the 2s2p 3P1 will also be presented. [1]Puchalski et al. PRA \textbf{87}, 030502(R) (2013) [Preview Abstract] |
Wednesday, May 30, 2018 8:24AM - 8:36AM |
H07.00003: Microwave-optical two photon excitation of Rydberg states Duncan Tate, Thomas Gallagher We report efficient microwave-optical two photon excitation of Rb Rydberg atoms in a magneto optical trap. This approach allows the excitation of normally inaccessible states and provides a path toward excitation of high angular momentum states. The efficiency stems from the elimination of the Doppler width, the use of a narrow band pulsed laser, and the enormous electric dipole matrix element connecting the intermediate and final states of the transition. The excitation is efficient in spite of the low optical and microwave powers, of order 1 kW and 1 mW, respectively. To our knowledge, this is the first application of the large dipole coupling strengths between Rydberg states to achieve two photon excitation of Rydberg atoms. [Preview Abstract] |
Wednesday, May 30, 2018 8:36AM - 8:48AM |
H07.00004: Quantum beat spectroscopy of Rydberg hyperfine structure Huy Nguyen, Jacob Lampen, Matthew Winchester, Paul Berman, Alex Kuzmich Measurements of the hyperfine interval $\nu_{hfs}$ for highly excited Rydberg levels are challenging since the interval scales inversely with principal quantum number $\propto n^{-3}$. In our experiment a sample of ultra-cold Rb atoms is prepared in a state-insensitive lattice to preserve ground-Rydberg atomic coherence. A two-photon 5s-ns transition is used to excite a manifold of nuclear Zeeman states in the Paschen-Back regime with energy splittings $\approx \nu_{hfs}/4$. Time-dependent atomic interference between the nuclear Zeeman states modulates the polarization of the coherently retrieved light field on a $\sim10\mu s$ timescale. The effect of nuclear state dependent light shifts on the observed beat frequency is investigated, and $\nu_{hfs}$ is measured for principal quantum numbers between 30 and 50. [Preview Abstract] |
Wednesday, May 30, 2018 8:48AM - 9:00AM |
H07.00005: Abstract Withdrawn
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Wednesday, May 30, 2018 9:00AM - 9:12AM |
H07.00006: Measurement of the lifetime of the 7S1/2 state in atomic cesium using asynchronous gated detection Yao De George Toh, Jose A. Jaramillo-Villegas, Nathan Glotzbach, Jonah Quirk, Ian C. Stevenson, Jungo Choi, Andrew M. Weiner, Daniel S. Elliott Our group is making progress towards new parity violation measurements in cesium. Atomic lifetime measurements provide sensitive tests of theoretical models of the cesium atom, which play a central role in parity violation measurements. We report a measurement of the lifetime of the cesium $7s^2~S_{1/2}$ state using time-correlated single photon counting spectroscopy. We excite the atoms using a Doppler-free two-photon transition from the ground state, and detect the $1.47~\mu m$ photons from spontaneous decay. We introduce an asynchronous detection technique using gated single photon detectors, allowing us to capture the fluorescence profile for a time window much larger than the detector gate length. [Preview Abstract] |
Wednesday, May 30, 2018 9:12AM - 9:24AM |
H07.00007: Effects of spin-exchange collisions on atomic radio-frequency spectroscopy Chuanpeng Hao, Yuan Zhu, Zheru Qiu, Qi Sun, Dong Sheng A far-off-resonance radio-frequency (rf) field, oscillating in the direction perpendicular to the bias magnetic field, could modify the atomic gyromagnetic ratio. In cases of negligible atomic collisions, it has been well established that the modified gyromagnetic ratio is a zero-order Bessel function of the rf field parameters. In this talk, we show our efforts to study this spectroscopy in presence of strong spin-exchange collisions. We focus on the spin-exchange-relaxation-free (SERF) regime where spin-exchange collisions are much faster than the spin precession. In this regime, the modified atomic gyromagnetic ratio shows different relations with the rf field parameters, depending on the spin-exchange collision rate, bias magnetic field amplitude, and nuclear spin number. A surprising turning point appears when the spin-exchange collision rate is comparable with the rf field detuning. [Preview Abstract] |
Wednesday, May 30, 2018 9:24AM - 9:36AM |
H07.00008: Measurement and identification of EUV spectra from highly charged Yb in an electron beam ion trap Yuri Ralchenko, Roshani Silwal, N/A Dipti, Joan M. Dreiling, Samuel Sanders, B. Hemalatha Rudramadevi, John D. Gillaspy, Endre Takacs Extreme ultraviolet (EUV) spectra of Rb-like Yb$^{33+}$ through Na-like Yb$^{59+}$ ions were produced and accurately measured in an electron beam ion trap at National Institute of Standards and Technology. The EUV radiation was observed with a flat-field grazing incidence spectrometer in the wavelength region of 2 nm to 26 nm. The electron beam energies were varied between 1.6 keV and 8.6 keV to distinguish between different N- and M-shell ions. More than 100 new spectral lines due to $\Delta n$=0 electric-dipole and magnetic-dipole transitions were unambiguously identified using large-scale collisional-radiative (CR) simulations of non-Maxwellian EBIT plasma with the code NOMAD. The CR model included nearly 74,000 levels from about 30 ions of Yb which allowed us to reach a comprehensive description of level population kinetics. Also the Na-like D$_1$ 3s$_{1/2}$--3p$_{1/2}$ and D$_2$ 3s$_{1/2}$--3p$_{3/2}$ lines were measured at the electron beam energy of 18 keV thereby providing a test of relativistic and quantumelectrodynamic effects on atomic structure of highly-charged ions. Detailed comparisons between measurements and simulations will be presented. [Preview Abstract] |
Wednesday, May 30, 2018 9:36AM - 9:48AM |
H07.00009: Theoretical and experimental studies of absolute absorption of a lithium vapor cell. Leonardo de Melo, Jiaming Li, Le Luo We report measurements of absolute absorption of a thermal lithium atomic vapor with argon buffer gas. A non-trivial beam profile dependent saturation absorption has been observed and compared with an atomic model that self-consistently couples optical pumping of hyperfine states, spatial evolution of laser beam intensity and gas dynamics including velocity changing collisions with buffer gas. The quantitative agreement between measurements and simulations confirms that the interplay between atomic state dynamics, optical beam evolution, and velocity changing collisions account for the absorption spectra and the beam profile effects in an ensemble of thermal atomic vapor and buffer gas. [Preview Abstract] |
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