Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session C4: Atomic and Molecular Structure and Spectroscopy |
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Chair: Stephen Lundeen, Colorado State University Room: 204 |
Tuesday, June 4, 2013 2:00PM - 2:12PM |
C4.00001: Microwave spectroscopy of High-L n$=$28 Rydberg levels of Th2$+$: Polarizabilities and Moments of Fr-like Th3$+$ Julie Keele, Chris Smith, Stephen Lundeen, Charles Fehrenbach Using the microwave/RESIS technique, the relative positions of twenty Rydberg levels in n$=$28 of Th$^{\mathrm{2+}}$ with L $=$ 9, 10, 11, and 12 have been determined with MHz precision. This structure pattern was analyzed to extract measurements of several important properties of the Fr-like Th$^{\mathrm{3+}}$ ion that forms the core of this Rydberg system. Among the properties so determined are the quadrupole and hexadecapole moments, the scalar and tensor dipole polarizabilities, and the scalar quadrupole polarizability. The analysis includes significant non-adiabatic corrections. [Preview Abstract] |
Tuesday, June 4, 2013 2:12PM - 2:24PM |
C4.00002: Precision Radio Frequency Spectroscopy in the $^{137}$Ba$^+$ 5D$_{5/2}$ Manifold Matthew Hoffman, Spencer Williams, Anupriya Jayakumar, E.N. Fortson, Boris B. Blinov As atomic theorists' computational techniques become increasingly accurate and sophisticated, precision experiments are necessary to confirm the results of these calculations. The substructure of the long-lived 5D$_{5/2}$ level of $^{137}$Ba$^{+}$ is an ideal testing ground, where calculations are limited by uncertainty in the wavefunctions used. The intervals of this hyperfine manifold are parameterized to first-order by the well-studied nuclear magnetic dipole moment ($\mu$) and the electric quadrupole moment (Q). However, the presence of a nuclear magnetic octupole moment, $\Omega$, as well as second-order corrections in the hyperfine interaction of the same magnitude as $\Omega$, offer additional contributions which are measurable using precision radio-frequency (rf) spectroscopy.\footnote{Phys. Rev. A 77, 052503 (2008)} By accurately measuring hyperfine intervals with transitions that are insensitve to magnetic field to first order, and using results from the 5D$_{3/2}$ level,\footnote{Opt. Express 20, 21379-21384 (2012)} we can extract $\Omega$ as well as the magnitude of the second order corrections to compare with theory. [Preview Abstract] |
Tuesday, June 4, 2013 2:24PM - 2:36PM |
C4.00003: A novel technique for measuring the microwave transitions and the indirect spin-orbit splittings in the high angular momentum Rydberg states of barium Jirakan Nunkaew, Evan Kim, Thomas Gallagher We use a novel detection technique, selective laser excitation to the autoionizing states, to observe the microwave transitions of Ba from $6sng$ to $6snh$, $6sni$ and $6snk$ for $n$= $15$, $16$, $17$ and $18$. We extract the dipole and quadrupole polarizabilities of Ba$^+$ from the measured intervals between the $6snh-6sni$ and $6sni-6snk$ states of Ba using the non-adiabatic core polarization model. The values we determine for the dipole and quadrupole polarizabilities are $\alpha_d=129.03(57)\;a_0^3$ and $\alpha_q=1790(76)\; a_0^5$, respectively. The energies of the $6sn\ell$, $\ell\geq5$ states are split by the indirect spin-orbit coupling of the Ba core to the Rydberg electron, producing the $K$ splittings. From the $K$ splittings we extract the ionic dipole and quadrupole matrix elements, $<6s|r|6p>=4.10(9)\;a_0$ and $<6s|r^2 |5d>=9.64(15)\;a_0^2$, respectively. [Preview Abstract] |
Tuesday, June 4, 2013 2:36PM - 2:48PM |
C4.00004: Microwave spectroscopy of High-L n$=$9 levels of Nickel: Polarizabilities and Moments of the Ni$^{+}$ ion Chris Smith, Shannon Woods, Julie Keele, Stephen Lundeen The complete pattern of binding energies of n$=$9 Rydberg levels of Nickel with L $=$ 6, 7, and 8 has been measured precisely using the microwave/RESIS technique. Analysis of the level pattern using the adiabatic effective potential model [1] yields measurements of several significant properties of the Ni$^{+}$ core ion. Among these are the permanent electric quadrupole and hexadecapole moments, the magnetic dipole moment, the scalar and tensor dipole polarizabilities, and the scalar quadrupole polarizability.\\[4pt] [1] Shannon L. Woods and S.R. Lundeen, Phys. Rev. A 85, 042505 (2012). [Preview Abstract] |
Tuesday, June 4, 2013 2:48PM - 3:00PM |
C4.00005: Exact Atomic-Pair-Interaction Representations of Molecular Hamiltonian Matrices P.W. Langhoff, M. Ben-Nun, K. Rollin, J.D. Mills, J.A. Boatz, R.J. Hinde, G.A. Gallup Progress is reported in the implementation of a novel theoretical method for ab initio calculations of molecular potential energy surfaces. The theory is based on use of (Eisenschitz-London) products of atomic spectral eigenstates in the absence of explicit aggregate antisymmetry. An exact atomic-pair-interaction theorem is devised for such atomic spectral product Hamiltonian matrices. It is shown that atomic pair antisymmetry, which is enforced subsequent to matrix construction, is sufficient to exclude the non-Pauli solutions of the Schr\"odinger equation spanned by the atomic product representation. Aspects of a computer code suite devised to perform such calculations are described, including calculations of many-electron atomic eigenstates and pairwise atomic interactions employing valence bond methods in even-tempered Slater-orbital basis sets, enforcement of atomic pairwise antisymmetry employing diatomic metric matrices, use of Wigner rotation matrices for the angular degrees of freedom of atomic interaction matrices, and spin re-coupling formalism. Illustrative small molecule and cluster applications provide potential energy surfaces in agreement with fully antisymmetric valence-bond results, including avoided crossings and conical intersections in excited states. [Preview Abstract] |
Tuesday, June 4, 2013 3:00PM - 3:12PM |
C4.00006: Precision Laser Spectroscopy of Lithium William A. van Wijngaarden, Jie Wang, Bin Jian A number of recent experiments have employed novel spectroscopic techniques to precisely measure the fine and hyperfine structure splittings as well as the isotope shifts for several transitions at optical frequencies for the stable ($^{6,7}$Li) and radioactive isotopes ($^{8,9,11}$Li) of lithium. These data offer an important test of theoretical techniques that have been developed over the last decade by several groups to accurately calculate effects due to Quantum Electrodynamics and the finite nuclear size in 2 and 3 electron atoms. Theory and experiment have studied several transitions in both singly ionized lithium and neutral lithium. The work by multiple groups permits a critical examination of the consistency of separately, the experimental work as well as the theoretical calculations. Combining the measured isotope shifts with the calculated energy shifts passing these consistency tests, permits the determination of the relative nuclear charge radius with an uncertainty approaching 1 $\times$ 10$^{-18}$ meter. These results are about two orders of magnitude more accurate than those obtained by electron scattering experiments and give insight into the mass and charge distributions of the nuclear constituents. [Preview Abstract] |
Tuesday, June 4, 2013 3:12PM - 3:24PM |
C4.00007: Suppression of Allowed Transitions in Al-like Krypton (Kr$^{23+}$) Due to the Presence of a Magnetic Dipole Transition in the 3s$^2$3p $^2$P Ground Term Joseph Reader, Yuri Podpaly, Yuri Ralchenko, John Gillaspy Extreme ultraviolet spectra of highly charged krypton atoms were produced with an electron beam ion trap (EBIT) and recorded with a flat-field grazing-incidence spectrometer. The wavelength range was 3-18 nm. Wavelength calibration was provided by known lines of highly ionized Kr as well as spectra of C, O, Xe, and Ba. The observed spectra were interpreted with the aid of collisional-radiative modeling of the EBIT plasma. For the Al-like ion Kr$^{23+}$ the allowed resonance lines 3s$^{2}$3p $^{2}$P-3s$^{2}$3d $^{2}$D exhibited extreme deviation from the normal ratios for lines of this multiplet. In particular, the $^{2}$P$_{3/2}$-$^{2}$D$_{5/2}$ transition, normally the strongest, was observed to be the weakest. This effect was explained by the fact that in the low electron density environment of EBIT the $^{2}$D$_{5/2}$ level is primarily populated by electron excitation from $^{2}$P$_{3/2}$. However, the presence of a magnetic dipole M1 transition 3s$^{2}$3p $^{2}$P$_{1/2}$-$^{2}$P$_{3/2}$ reduces the population of $^{2}$P$_{3/2}$ and hence the population of $^{2}$D$_{5/2}$. We are conducting further modeling with varying electron density to try to reproduce the observed line ratios. This could serve as a diagnostic tool for determining electron density in EBIT and fusion energy devices. [Preview Abstract] |
Tuesday, June 4, 2013 3:24PM - 3:36PM |
C4.00008: Precision Spectroscopy of Tellurium James Coker, John Furneaux Tellurium (Te$_2$) is widely used as a frequency reference, and although a standard atlas encompassing over 5200~cm$^{-1}$ already exists [1], Doppler broadening present in that work buries a significant portion of the features. More recent but less complete studies of Te$_2$ exist which do not exhibit Doppler broadening [2-4], and this work adds to that knowledge a few hundred transitions in the vicinity of 444~nm. Using a Fabry Perot cavity in a shock-absorbing, temperature and pressure regulated chamber, locked to a Zeeman stabilized HeNe laser, we measure changes in frequency of our diode laser to $\sim$1~MHz precision. This diode laser is scanned over 1000 GHz for use in a saturated-absorption spectroscopy cell filled with Te$_2$ vapor. This data allows for new studies of the excited states of Te$_2$.\\[4pt] [1] J.~Cariou, and P.~Luc, Atlas du spectre d'absorption de la molecule de tellure, Laboratoire Aime-Cotton (1980).\\[0pt] [2] J.~Verges et~al., Physica Scripta {\bf 25}, 338 (1982).\\[0pt] [3] Ph.~Courteille et~al., Appl. Phys. B {\bf 59}, 187 (1994)\\[0pt] [4] T.J.~Scholl et~al., J. Opt. Soc. Am. B {\bf 22}, 1128 (2005). [Preview Abstract] |
Tuesday, June 4, 2013 3:36PM - 3:48PM |
C4.00009: Measurement of the 6S$_{1/2}$ $\rightarrow$ 5D$_{3/2}$ Magnetic Dipole Transition Amplitude in Ba$^{+}$ and Application to a Parity Nonconservation Measurement Spencer Williams, Anupriya Jayakumar, Matthew Hoffman, Boris Blinov, Norval Fortson We present two approaches for measuring the 6S$_{1/2}$ $\rightarrow$ 5D$_{3/2}$ magnetic dipole transition amplitude (M1) in $^{137}$Ba$^{+}$ and $^{138}$Ba$^{+}$ using a frequency stabilized 2.051 micron laser. In the odd isotope, M1 can be measured directly by driving the weak 6S$_{1/2}$($F=1$) $\rightarrow$ 5D$_{3/2}$($F=0$) transition where the electric quadrupole amplitude (E2) is explicitly zero. For measurement in the even isotope we propose to use laser polarization and magnetic field geometry to tune E2 to roughly the same order of magnitude as M1 for the 6S$_{1/2}$ ($m_{J}=1/2$) $\rightarrow$ 5D$_{3/2}$ ($m_{J}=1/2$) transition. M1 can then be extracted from the interference between the E2 and M1 amplitudes and prior knowledge of E2. This work will test state-of-the-art many-body calculations and is relevant to fundamental symmetry searches in atoms. In particular, we are motivated by our interest in measuring atomic parity nonconservation (PNC) in a single trapped barium ion, where the present work will provide essential knowedge of the magnitude of M1 and is an important proof-of-principle test of the method. [Preview Abstract] |
Tuesday, June 4, 2013 3:48PM - 4:00PM |
C4.00010: Time-Resolved Surface-Enhanced Coherent Sensing of Nanoscale Molecular Complexes George R. Welch, Dmitri V. Voronine, Alexander M. Sinyukov, Xia Hua, Kai Wang, Pankaj K. Jha, Elango Munusamy, Steven E. Wheeler, Alexei V. Sokolov, Marlan O. Scully Nanoscale real-time molecular sensing requires large signal enhancement, small background, short detection time and high spectral resolution. We demonstrate a new vibrational spectroscopic technique which satisfies all of these conditions. This time-resolved surface-enhanced coherent anti-Stokes Raman scattering (tr-SECARS) spectroscopy is used to detect hydrogen-bonded molecular complexes of pyridine with water in the near field of gold nanoparticles with large signal enhancement and a fraction of a second collection time. Optimal spectral width and time delays of ultrashort laser pulses suppress the surface-enhanced non-resonant background. Time-resolved signals increase the spectral resolution which is limited by the width of the probe pulse and allow measuring nanoscale vibrational dephasing dynamics. This technique combined with quantum chemistry simulations may be used for the investigation of complex mixtures at the nanoscale and surface environment of artificial nanostructures and biological systems. [Preview Abstract] |
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