Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session N7: Atomic and Molecular Structure and Spectroscopy I |
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Chair: Joseph Tan, NIST Room: Terrace |
Thursday, June 7, 2012 10:30AM - 10:42AM |
N7.00001: Spectroscopy of HfF$^{+}$ for the JILA electron electric dipole moment search Daniel Gresh, Kevin Cossel, Tyler Coffey, Laura Sinclair, Jun Ye, Eric Cornell A low lying $^{3}\Delta _{1}$ state in HfF$^{+}$ and ThF$^{+}$ is an ideal candidate for a precise measurement of the electron electric dipole moment (eEDM). However, the electronic level structure of these species is not very well studied, and theoretical uncertainties are on the order of 1000 cm$^{-1}$ for many levels. We have used a recently developed novel technique, frequency comb velocity modulation spectroscopy (VMS), as well as cw-laser VMS for high-sensitivity, high-resolution, ion sensitive detection from 675-1000 nm (10000-14700 cm$^{-1})$. We report the measurement and assignment of 15 ro-vibrational bands in HfF$^{+}$ including accurate fits for the $^{3}\Delta _{1}$ metastable state and the $^{1}\Sigma ^{+}$ ground state. In addition, we have characterized six excited states and discuss the implications for state preparation and readout in the eEDM experiment. This system will allow rapid characterization of ThF$^{+}$, which should further improve the sensitivity of the eEDM experiment. In addition to supporting the eEDM experiment, these studies provide data for testing and refining relativistic molecular structure calculations. [Preview Abstract] |
Thursday, June 7, 2012 10:42AM - 10:54AM |
N7.00002: Calculation of \textit{ab initio} potential curves for ground and low lying excited states of heteronuclear alkaline earth dimers BeCa$^+$, BeMg$^+$ and MgCa$^+$ Sandipan Banerjee, John Montgomery, Robin C\^ot\'e We report \textit{ab initio} calculations on the ground and low lying excited states of $^2\Sigma$ and $^2\Pi$ symmetry for BeCa$^+$, BeMg$^+$ and MgCa$^+$. Valence multireference configuration interaction (MRCI) calculations were performed using complete active space self consistent field (CASSCF) orbitals. We use augmented correlation consistent valence quintuple zeta (aug-cc-pV5Z) basis set for our valence calculations. Core-valence and scalar relativistic effects are included at the CCSDT/cc-pwCVTZK level of theory. Spectroscopic constants and bound vibrational levels are calculated, as well as Frank-Condon factors and electronic dipole transition moments between the dipole--allowed states. The static dipole and quadrupole polarizabilities, along with long range expansion coefficients are also reported. [Preview Abstract] |
Thursday, June 7, 2012 10:54AM - 11:06AM |
N7.00003: Improved Energy Bounds and Basis Set Construction Strategies for Lithium Gordon Drake, Liming Wang, Zong-Chao Yan Improved nonrelativistic energy bounds for the low-lying states of lithium are presented using the variational method in Hylleraas coordinates. For example, the nonrelativistic energies for the infinite nuclear mass case are $-7.478\,060\,323\,910\,147(1)$~a.u. for $1s^22s\, ^2\!S$, $-7.354\,098\,421\,444\,37(1)$~a.u. for $1s^23s\, ^2\!S$, $-7.318\,530\,845\,998\,91(1)$~a.u. for $1s^24s\, ^2\!S$, $-7.410\,156\,532\,652\,4(1)$~a.u.~for $1s^22p\, ^2\!P$, and $-7.335\,523\,543\,524\,688(3)$ ~a.u.~for $1s^23d\, ^2\!D$. The completeness of the angular momentum and spin configurations is investigated and examples presented for the $2P$ and $3D$ states to demonstrate the effect of different coupling schemes. In particular, the so-called second spin function (i.e.\ coupled to form an intermediate triplet state) is shown to have no effect on the final converged results, even for the expectation values of spin-dependent operators. [Preview Abstract] |
Thursday, June 7, 2012 11:06AM - 11:18AM |
N7.00004: Measurement of the first tune-out wavelength of K with an atom interferometer William Holmgren, Raisa Trubko, Ivan Hromada, Alex Cronin We present a measurement of the tune-out wavelength of K between the D1 and D2 lines with picometer uncertainty. Tune-out wavelengths occur where the dynamic polarizability of an atom equals zero between two transitions [1,2]. We find the tune-out wavelength by focusing a laser beam on one path of an atom interferometer and measuring the differential phase shift as a function of laser wavelength. Our tune-out wavelength measurements can be excellent tests of atomic structure calculations because they are insensitive to systematic errors due to light intensity, atom beam velocity, and light polarization. Additionally, multi-species optical traps operating at tune-out wavelengths may yield new insights into many-body physics and quantum information processing. We will also discuss the feasibility of measurements of tune-out wavelengths in other atoms in our lab. This work is supported by the NSF and NIST. \\[4pt] [1] L.J. LeBlanc and J.H. Thywissen, Phys. Rev. A 75, 053612 (2007).\\[0pt] [2] B. Arora, M.S. Safronova, and C.W. Clark, Phys. Rev. A 84, 043401 (2011). [Preview Abstract] |
Thursday, June 7, 2012 11:18AM - 11:30AM |
N7.00005: The observation of the dipole-dipole interaction by Ramsey method Hyunwook Park, Thomas Gallagher Previously, we reported a line broadening technique to quantitatively measure the dipole-dipole interaction in Rb Rydberg atoms[1]. As an alternative and more sensitive way, Ramsey interferometry is employed. Two identical microwave(MW) pulses, which are 200ns-long and separated by 300ns, are applied to Rb \textit{ns} Rydberg atoms to drive \textit{ns-np}$_{1/2}$ transitions ($n$=33, 36, 39, and 41). As the MW frequency is swept through the resonance, Ramsey fringes with different contrast are observed depending on the atomic density. The dipole-dipole interaction washes out the fringe contrast at high atomic density, while isolated atoms produce 100{\%} contrast Ramsey fringes. The interesting result is that the loss of the contrast as a function of the atomic density is not a linear process. The contrast drops rapidly with increasing density but it stops decreasing once it reaches at a certain non-zero contrast (Extremely high atomic density never completely destroys the contrast.). It turns out that the zero-shift dipole-dipole energy levels play a significant role in maintaining the contrast, even at very high atomic density. A simple model, based on the dipole-dipole interaction [1], reproduces the Ramsey lineshape including the surviving contrast at high density. \\[4pt] [1] Dipole-dipole broadening of Rb ns-np microwave transition, H Park et al. Phys. Rev. A 84, 022704 (2011). [Preview Abstract] |
Thursday, June 7, 2012 11:30AM - 11:42AM |
N7.00006: Long-range interactions between Mg atoms J.F. Babb The long-range interactions between two and three Mg atoms, the interaction between a Mg atom and a perfectly conducting metallic plate, and between a Mg atom and two plates are calculated. The atomic electric-dipole oscillator strength distribution is composed from combinations of theoretical and experimental data for energy levels, oscillator strengths, the polarizability, and photoionization cross sections. [Preview Abstract] |
Thursday, June 7, 2012 11:42AM - 11:54AM |
N7.00007: Properties of Rn-like Th$^{4+}$ from microwave spectroscopy of high-L n=37 Rydberg states of Th$^{3+}$ Chris Smith, Julie Keele, Stephen Lundeen, Charles Fehrenbach A recent microwave/RESIS study of n=37 Rydberg levels of Th$^{3+}$ led to the first measurements of dipole and quadrupole polarizabilities of Rn-like Th$^{4+}$ [1]. We report additional measurements that extend the data pattern to include the L=8 level and improve the precision of the L = 14 and L = 15 levels. Together these new measurements allow improved determinations of both polarizabilities and a more precise test of theoretical calculations [2].\\[4pt] [1] Julie A. Keele, S.R. Lundeen, and C.W. Fehrenbach, Phys. Rev. A \underline {83}, 062509 (2011)\\[0pt] [2] U.I Safronova and M.S. Safronova, Phys. Rev. A \underline {84}, 052515 (2011) [Preview Abstract] |
Thursday, June 7, 2012 11:54AM - 12:06PM |
N7.00008: Properties of Fr-like Th$^{3+}$ from microwave spectroscopy of high-L Rydberg states of Th$^{2+}$ Julie Keele, Chris Smith, Shannon Woods, Stephen Lundeen, Charles Fehrenbach Spectroscopy of high-L n= 28 Rydberg levels of Th$^{2+}$ was recently reported using the optical RESIS method [1]. Because the ground state of Fr-like Th$^{3+}$ is a $^{2}$F$_{5/2}$ level, each (n,L) Rydberg level of Th$^{2+}$ is split into six eigenstates whose relative positions are determined by long-range e-Th$^{3+}$ interactions. Measurements of those positions can be used to determine the Th$^{3+}$ properties that control those interactions, such as polarizabilities and permanent moments. We report a much improved study of n=28 levels with 9 $\le $ L $\le $ 12, obtained with the microwave/RESIS method. The higher precision measurements allow improved determinations of a wider range of Th$^{3+}$ properties and a better test of theoretical calculations [2].\\[4pt] [1] Julie A. Keele, M.E. Hanni, Shannon L. Woods, S.R. Lundeen, and C.W. Fehrenbach, Phys. Rev. A \underline {83}, 062501 (2011)\\[0pt] [2] U.I. Safronova, W.R. Johnson, and M.S. Safronova, Phys. Rev. A \underline {74}, 042511 (2006) [Preview Abstract] |
Thursday, June 7, 2012 12:06PM - 12:18PM |
N7.00009: Relativistic many-body calculations of energies in a broad range of Lu-like ions from W$^{3+}$ to Fm$^{29+}$ U.I. Safronova, A.S. Safronova Energies of the [Xe]$4f^{14}5d^3$, [Xe]$4f^{14}5d^26s$, [Xe]$4f^{14}5d^26p$, and [Xe]$4f^{14}5d6s6p$ states of lutetiumlike ions with $Z$ = 74-100 are determined using second-order relativistic many-body perturbation theory (RMBPT). Our calculations start from a Er-like Dirac-Fock potential ([Xe]$4f^{14}$ where [Xe]=$1s^22s^22p^63s^23p^63d^{10}4s^24p^64d^{10}5s^25p^6$). Second-order Coulomb and Breit-Coulomb interactions are included. Correction for the frequency-dependence of the Breit interaction as well as Lamb shift correction to energies are taken into account in lowest order. The three-electron contributions to the energy are compared with the one- and two-electron contributions. They are found to contribute about 10-20\% of the total second-order energy. The ratio of the third-order and second-order corrections to the one-electron contributions is found to be about 5-10\%. A detailed discussion of the various contributions to the energy levels is given for Lu-like tungsten (Z=74). Trends of excitation energies including splitting of the doublet and quartet terms as functions of nuclear charge $Z$ = 71--100 are illustrated graphically for some states. This research was sponsored by DOE under the OFES grant DE-FG02-08ER54951. [Preview Abstract] |
Thursday, June 7, 2012 12:18PM - 12:30PM |
N7.00010: Relativistic many-body calculation of energies, oscillator strengths, transition rates, lifetimes, multipole polarizabilities, and hyperfine constants of Th~IV ion Marianna Safronova, Ulyana Safronova Atomic properties of the 24 low-lying $ns$, $np_j$, $nd_j$, $nf_j$, and $ng_j$ states in Th~IV ion are calculated using the high-precision relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Recommended values are provided for a large number of electric-dipole matrix elements, oscillator strengths, transition rates, and lifetimes. Scalar polarizabilities of the ground and six excited states ($5f_j$, $6d_j$, $7p_j$, and $7s$ states), and tensor polarizabilities of the $5f_j$, $6d_j$, and $7p_{3/2}$ states are evaluated. The uncertainties of the recommended values are estimated. The hyperfine structure of the $^{229}$Th~IV ion is investigated. The hyperfine $A$- and B-values are determined for the low-lying levels listed above. These calculations provide recommended values critically evaluated for their accuracy for a number of Th~IV atomic properties for use in theoretical modeling as well as in planning and analysis of various experiments including RESIS studies of actinide ions and development of ultraprecise nuclear clock. [Preview Abstract] |
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