Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session N5: Atomic Spectroscopy I |
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Chair: Sergey Porsev, University of Delaware, USA and PNPI, Russia Room: Fairfield |
Thursday, June 11, 2015 10:30AM - 10:42AM |
N5.00001: Microwave spectroscopy of the calcium $4snf\rightarrow4s(n+1)d$, $4sng$, $4snh$, $4sni$, and $4snk$ transitions Jirakan Nunkaew, Tom Gallagher We use a delayed field ionization technique to observe the microwave transitions of calcium Rydberg states, from the $4snf$ states to the $4s(n+1)d$, $4sng$, $4snh$, $4sni$, and $4snk$ states for $18\leq n\leq23$. We analyze the observed intervals between the $\ell$ and $(\ell+1)$, $\ell\ge5$, states of the same $n$ to determine the Ca$^+$ $4s$ dipole and quadrupole polarizabilities. We show that the adiabatic core polarization model is not adequate to extract the Ca$^+$ $4s$ dipole and quadrupole polarizabilities and a non adiabatic treatment is required. We use the non adiabatic core polarization model to determine the ionic dipole and quadrupole polarizabilities to be $\alpha_d=76.9(3)$ a$_0^3$ and $\alpha_q=206(9)$ a$_0^5$, respectively. [Preview Abstract] |
Thursday, June 11, 2015 10:42AM - 10:54AM |
N5.00002: Complex polarizabilities of atoms and ions Michael Bromley, Swaantje Grunefeld, Julia Rossi, Li-Yan Tang, Yongjun Cheng, Jun Jiang, Julian Berengut, Jim Mitroy The complex dipole polarizabilities of neutral alkali atoms are computed for several low-lying eigenstates. We present a unified view of the frequency dependence of the complex polarizabilities spanning below and above the various ionization thresholds as well as through the Rydberg transitions. We have adapted the methodology previously developed by Langhoff and collaborators that uses the pseudostate energy spectrum and wavefunctions to describe the above threshold physics. This enables the real part of the polarizability to be computed as well as simultaneously computing two different contributions to the imaginary part of the polarizability. The absorption polarizability is related to the photoabsorption cross-section both below and above threshold, whilst the ionization polarizability describes the photoionization cross-section above threshold. We also present an extension the Langhoff method to calculations of the complex hyperpolarizabilities of atoms and ions that describes how atomic clocks are impacted by the non-linear optics of light-atom interactions. [Preview Abstract] |
Thursday, June 11, 2015 10:54AM - 11:06AM |
N5.00003: CI-MBPT energy levels of four-valent Si I Igor Savukov The mixed configuration-interaction many-body perturbation theory (CI-MBPT) method is accurate in divalent atoms. In more complex atoms, with the number of valence electrons it becomes progressively more difficult to saturate CI space. Here a four-valence electron atom, Si I, is considered. It is found that by using a relatively small cavity of 30 a.u. and by choosing carefully configuration space, it is possible to obtain quite accurate agreement between the theory and experiment. After subtraction of systematic shifts of 481 cm$^{-1}$ and -426 cm$^{-1}$ for the lowest even states and odd states respectively, the deviation between theory and experiment becomes at the level of 100 cm$^{-1}$. This agreement is comparable to that in divalent atoms where the CI saturation has been achieved. It is anticipated that the approach can also give good results for atoms with more valence electrons to be considered in the future. [Preview Abstract] |
Thursday, June 11, 2015 11:06AM - 11:18AM |
N5.00004: Correlation effects in La, Ce, and lanthanide ions Charles W. Clark, Marianna Safronova, Ulyana Safronova We carry out a comprehensive study of higher-order correlation effects to the excitation energies of La, La$^+$, Ce, Ce$^+$, Ce$^{2+}$, and Ce$^{3+}$. The calculations are carried out using two hybrid approaches that combine configuration interaction with second-order perturbation theory and the linearized coupled-cluster all-order method. Use of two approaches allows us to isolate the effects of third- and higher-order corrections for various configurations. Comparison of results for monovalent and multivalent systems allowed us to separately study the importance of the core-valence and valence-valence correction. We also study the contribution of higher partial waves and investigate methods to extrapolate the effect of omitted partial waves. The effects of the higher partial waves for the monovalent configuration of La$^{2+}$ and Ce$^{3+}$ are compared with analogous effects in multivalent configurations of La, La$^+$, Ce, Ce$^+$, and Ce$^{2+}$. Tests of our extrapolation techniques are carried out for several Cd-like lanthanide ions. The results of the present studies are of particular interest to the development of high-precision methods for treatment of systems with partially filled $nf$ shells that are of current experimental interest for a diverse set of applications. [Preview Abstract] |
Thursday, June 11, 2015 11:18AM - 11:30AM |
N5.00005: Large-scale relativistic calculations of ionization energies and total binding energies of all atoms and positive atomic ions with nuclear charge $Z = $ 1-110 Alexander Kramida, Charlotte Froese Fischer, Joseph Reader, Paul Indelicato The latest versions of advanced multiconfiguration Dirac-Fock atomic codes, MCDFGME and Grasp2K, are used to calculate ionization energies (IE) and total binding energies of all atomic systems. Comparison with experiment and other benchmark data shows an excellent accuracy achieved in these calculations for H-, He-, and Li-like ions. In particular, our results for H-like ions with $Z$ \textgreater 2, obtained with the MCDFGME code, are the most accurate available today. For multi-electron ions, we combine the accurate single-configuration MCDFGME calculations with the correlation-difference energy (difference between the multiconfiguration and single-configuration total energies) calculated with Grasp2K. This approach results in a dramatically improved agreement of calculated IEs with experiment (less than 0.7 eV on average) for all systems, excluding those involving open $f$-shells. The most probable ground states are found for most systems, leaving questionable only about 100 out of total 6105 considered systems. [Preview Abstract] |
Thursday, June 11, 2015 11:30AM - 11:42AM |
N5.00006: Dielectronic recombination of Zn-like W$^{44+}$ from Cu-like W$^{45+}$ U.I. Safronova, A.S. Safronova Energy levels, radiative transition probabilities, and autoionization rates for [Ar]$3d^{10}4l'nl$ ($n$=4-12, $l \le n-1$), [Ar]$3d^{10}5l'nl$ ($n$=5-8, $l \le n-1$), and [Ar]$3d^{9}4l'4l''nl$ ($n$=4-5, $l \le n-1$) states in Zn-like tungsten (W$^{44+}$) are calculated using the Hartree-Fock-Relativistic method (COWAN code), the Multiconfiguration relativistic Hebrew University Lawrence Atomic Code (HULLAC code), and the relativistic many-body perturbation theory method (RMBPT code). Autoionizing levels above the thresholds [Ar]$3d^{10}4s$ are considered. It is shown that the contribution of the highly excited states is very important for the calculation of total DR rates. Contributions to DR rate from the excited [Ar]$4l'nl$ states with $n \ge 13$ and [Ar]$4l'nl$ states with $n \ge 8$, and additionally from core-excited [Ar]$3d^94l'4l''nl$ states with $n \ge 5$ are estimated by extrapolation of all atomic parameters. The total DR rate coefficient is derived as a function of electron temperature. Synthetic dielectronic satellite spectra from Zn-like W are simulated in a broad spectral range from 4 to to 140\AA.~ These calculations provide highly accurate values for a number of W$^{44+}$ properties useful for a variety of applications, including fusion and HEDP applications. [Preview Abstract] |
Thursday, June 11, 2015 11:42AM - 11:54AM |
N5.00007: A robust, inexpensive wavelength meter using a commercial color sensors Tyler Jones, Nils Otterstrom, Jarom Jackson, James Archibald, Dallin Durfee Commercial color sensor chips are used in a variety of consumer electronics.~ Many are built to specifications far above those needed for their typical uses, some having temperature coefficients of only a few parts per million, and using precision 16 bit analog to digital converters.~ Using such a device, we were able to measure the wavelength of a laser with a precision of 0.01 nm with a calibration drift of similar magnitude over several days.~ Factors that influence the precision and accuracy, such as etalon effects in the sensor, temperature dependence, intensity variations, and timing, will be discussed. [Preview Abstract] |
Thursday, June 11, 2015 11:54AM - 12:06PM |
N5.00008: Rydberg Spectroscopy and imaging of single Holmium atoms James Hostetter, Jonathan Pritchard, Mark Saffman Neutral holmium with its large number of hyperfine ground states provides a promising approach for collective encoding of a multi-qubit register. Collective encoding relies on the use of Rydberg blockade to create a one-to-one correspondence between singly excited states of the atomic ensemble and logical register states. As a step towards collective encoding with Rydberg blockade in holmium we have precisely measured the energy of ns and nd Rydberg states from n$=$41-101 using MOT depletion spectroscopy[1]. These measurements have resulted in a precise determination of the first ionization potential as well as the quantum defects of the singlet ns and nd series. The strong 410.5 nm cooling transition with $\sim$ 33 MHz linewidth coupled with the large hyperfine splitting in the electronically excited state are predicted to enable fast, loss-free, and state sensitive measurements which are a prerequisite for collective encoding experiments. We report on progress towards single-atom trapping and state sensitive detection of holmium in a far off-resonant optical dipole trap. \\[4pt] [1] J. Hostetter, J. D. Pritchard, J. E. Lawler, and M. Saffman, Phys. Rev. A 91, 012507 (2015). [Preview Abstract] |
Thursday, June 11, 2015 12:06PM - 12:18PM |
N5.00009: Light shift and ac Stark Effect on Ladder-Type Electromagnetically Induced Transparency in Cold Cs Atom Chin Chun Tsai, Zong-Syun He, Li-Ren Liu Light shift and power broadening are usually occurred in a strong field such as experiments using pulsed lasers. However, these effects have been observed in a cw weak field regime by measuring the ladder-type electromagnetically induced transparency (EIT) in a magneto-optical trap (MOT) and a room-temperature cell as a reference simultaneously. The cesium atoms was trapped in a MOT with temperature about 200 $\mu$K and 10$^9$ atom/cm$^3$. A diode laser set on resonance to Cs $|6s\,^2S_{1/2}, F=4\rangle\rightarrow$ $|6p\,^2P_{3/2}, F=5\rangle$ as a probe field and a counter-propagating Tisapphire laser coupled $|6p\,^2P_{3/2}, F=5\rangle\rightarrow$ $|8s\,^2S_{1/2}, F=5\rangle$ to form a ladder-type EIT on both MOT and room-temperature cell. The line width of the EIT signal was broadened from 3.2 MHz to 25.2 MHz while the Rabi frequency of coupling laser changed from 1.5 MHz to 13.0 MHz. A light shift was measured from -0.2 MHz to +0.6 MHz as increasing the coupling power in MOT EIT while conditions on room-temperature EIT was fixed. A theoretical discussion and simulation are performed to compare with the experimental spectra. [Preview Abstract] |
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