Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session N6: Spectroscopy, Lifetimes, Oscillator Strengths |
Hide Abstracts |
Chair: Sultana Nahar, Ohio University Room: Knoxville Convention Center 301C |
Thursday, May 18, 2006 1:30PM - 1:42PM |
N6.00001: Fine structure measurements in high-L, n=17 and 20 Rydberg states of magnesium: A determination of the polarizabilities of Mg$^{+}$ Erica L. Snow, Laura E. Wright, Stephen R. Lundeen RESIS microwave techniques [1] have been used to directly measure the fine structure intervals between several n=17 and 20 high-L states of magnesium. The precision of these measurements and the access to higher-L Rydberg levels provide more than an order of magnitude improvement on the precision of the ionic polarizabilities as compared with previous experiment. [2] This offers an excellent experimental check on the a-priori atomic structure calculations. [1] R.A. Komara, M.A. Gearba, C.W. Fehrenbach and S.R. Lundeen, J. Phys. B: At. Mol. Opt. Phys. \textbf{38} S87 (2005). [2] B. J. Lyons and T. F. Gallagher, Phys. Rev. A \textbf{57}, 2426 (1998). [Preview Abstract] |
Thursday, May 18, 2006 1:42PM - 1:54PM |
N6.00002: Fine Structure Measurements in High-L Rydberg States of Argon. Laura E. Wright, Erica L. Snow, Stephen R. Lundeen, W. Gregg Sturrus A Doppler-tuned CO$_{2}$ laser has been used to study n=9 to n=17 excitation transitions in high-L Rydberg states of Argon, revealing fully-resolved fine structure patterns in states with 5 $\le $ L $\le $ 8. The experimental method is similar to that used previously to study Ba Rydberg levels[1]. A fast beam of Argon Rydberg states with n $\sim $ 9 is produced by charge exchange between a 9.5 keV Ar$^{+}$ beam and a 9F Rb Rydberg target. Argon atoms excited to n=17 by the CO$_{2}$ laser are detected by Stark ionization. The measured fine structure patterns are used to deduce the dipole polarizability and quadrupole moment of the $^{2}$P$_{3/2}$ ground state of Ar$^{+}$. [1] E.L. Snow, et. al., Phys. Rev. A 71, 022510 (2005) [Preview Abstract] |
Thursday, May 18, 2006 1:54PM - 2:06PM |
N6.00003: Hyperfine splitting of the $6s$ level in Rb and its hyperfine anomaly Adrian Perez-Galvan, Yanting Zhao, Luis Orozco We present a hyperfine splitting measurement on the $6s$ level in $^{85}$Rb and $^{87}$Rb. The source of atoms is a 30 cm long cell with the natural abundance of the two isotopes. The cell operates at room temperature in a controlled magnetic environment. Two step excitation through the $5P_{1/2}$ level with lasers at 795 nm and 1.3 $\mu$m allows us to study the hyperfine separation of the $6s$ level. Use of AM sidebands in the 1.3 $\mu$m laser produces in-situ calibration of the scan. Detection through changes in the absorption at 795 nm shows resonances with good signal to noise ratio to permit a preliminary measurement of the splittings to better than 0.4 MHz. This resolution allows quantitative extraction of the hyperfine anomaly, a manifestation of the space distribution of the nuclear magnetization, in the first excited state of the $s$ manifold. We compare our results with ab initio calculations to test the quality of their wave-functions at the nucleus. [Preview Abstract] |
Thursday, May 18, 2006 2:06PM - 2:18PM |
N6.00004: M\"{o}ssbauer Study of Eu$_{14}$MnSb$_{11}$ and Yb$_{14}$MnSb$_{11}$ Zintl Compounds. Durga Kafle, Dennis Brown Antimony-121 M\"{o}ssbauer effect measurements have been performed mainly on Eu$_{14}$MnSb$_{11}$ and Yb$_{14}$MnSb$_{11}$ zintl compounds, through the temperature range from 2 K to room temperature. The isomer shifts observed (-4.5mm/sec to --10.3 mm/sec and -7.7 mm/sec to --11.2 mm/sec, respectively) from the present study for both Eu$_{14}$MnSb$_{11}$ and Yb$_{14}$MnSb$_{11}$ zintl compounds are close to the values (-8.54mm/sec to --8.73mm/sec) obtained for InSb, the standard compound for antimony-121 M\"{o}ssbauer effect measurements. Isomer shift distribution fits by using a Voigt-based Gaussian distribution profile show distinct peaks at the corresponding average isomer shift values obtained from Lorentzian four-site fits for Eu$_{14}$MnSb$_{11. }$ The study of the temperature dependence of line broadening as well as hyperfine magnetic field confirms the existence of long-range magnetic ordering of antimony-121 in Eu$_{14}$MnSb$_{11 }$below 12 K which resulted in the transition temperature, $T_C $, of 12 K, whereas $T_C $ found in Yb$_{14}$MnSb$_{11}$ is 45 K. The linear fit of the natural logarithm of area versus temperature using the Debye model for the high-temperature limit gives the values of 185 K and 196 K for the Debye temperature for Eu$_{14}$MnSb$_{11 }$and Yb$_{14}$MnSb$_{11}$ zintl compounds, respectively. [Preview Abstract] |
Thursday, May 18, 2006 2:18PM - 2:30PM |
N6.00005: Lattice based spectroscopy on an even isotope of Yb Zeb Barber, Chad Hoyt, Chris Oates, Leo Hollberg Recent advances in neutral-atom optical lattice clocks are beginning to show the promise of this high accuracy, high stability clock scheme. Until now, experimental progress has focused on the naturally occurring $^{1}$S$_{0}-^{3}$P$_{0}$ transition in the odd isotopes of Sr and Yb. We present 1D lattice spectroscopy based on this transition in an even isotope of Yb using a magnetically induced spectroscopic method. This method utilizes a moderate ($\sim $1mT) magnetic field to mix the upper clock state with a nearby allowed state to create a nonzero excitation probability at the clock wavelength of 578.42nm. Narrow linewidths of $\sim $20Hz with good signal-to-noise ratios were observed and a Stark-free wavelength of 759.35+/-.02nm was measured using the $^{174}$Yb isotope. This simple method, whose frequency errors could be held well below 10$^{-17}$, is equally suitable for other atoms such as Sr, Ca, and Mg. Through eliminating errors associated with the Zeeman substructure of the odd isotopes, this method should accelerate high accuracy evaluation of current optical lattice clock experiments. [Preview Abstract] |
Thursday, May 18, 2006 2:30PM - 2:42PM |
N6.00006: 2p$_{3/2}^{-1}$3x$^{-1}$-3x$^{-1}$3d$^{-1}$ X-Ray satellites in the L$\alpha$$_{1}$ region of 4d transition elements Surendra Poonia The X-ray satellite spectra arising due to 2p$_{3/2}^{-1}$3x$^{-1}$-3x$^{-1}$3d$^{-1}$ (x $\equiv $ s, p, d) transition array, in elements with Z = 40 to 48, have been calculated, using available Hartree-Fock-Slater (HFS) data on 1s$^{-1}$-2p$^{-1}$3x$^{-1}$ and 2p$_{3/2}^{-1}$-3x$^{-1}$,3x'$^{-1}$ Auger transition energies. The relative intensities of all the possible transitions have been estimated by considering cross - sections for the Auger transitions simultaneous to a hole creation and then distributing statistically the total cross sections for initial two hole states 2p$_{3/2}^{-1}$3x$^{-1}$ amongst various allowed transitions from these initial states to 3x$^{-1}$3d$^{-1}$ final states by Coster-Kronig (CK) and shake off processes. In both these processes initial single hole creation is the prime phenomenon. Each transition has been assumed to give rise to a Gaussian line and the overall spectrum has been computed as the sum of these Gaussian curves. The calculated spectra have been compared with the measured satellite energies in L$\alpha _{1}$ spectra. Their intense peaks have been identified as the observed satellite lines. The peaks in the theoretical satellite spectra were identified as the experimentally reported satellites $\alpha _{3}$, $\alpha _{4}$ and $\alpha _{5}$, which lie on the high-energy side of the L$\alpha _{1}$ dipole line. [Preview Abstract] |
Thursday, May 18, 2006 2:42PM - 2:54PM |
N6.00007: L$\beta$ $_{2 }$ satellites in the X-ray emission spectra of 5d transition elements Surendra Poonia The X-ray satellite spectra arising due to L$_{3}$M$_{x}-$M$_{x}$N$_{4,5}$ (x $\equiv $ 1-5) transition array, in elements with Z = 74 to 90, have been calculated. The energies of various transitions of the array have been determined by using available HFS data on K-LM and L-MN Auger transition energies, their relative intensities have been estimated by considering cross sections of singly ionized L$_{3}$M$_{x}$ (x $\equiv $ 4, 5) states and then of subsequent Coster-Kronig (CK) and shake off processes. The calculated spectra have been compared with the measured satellite energies in L$\beta _{2}$ spectra. The peaks in the theoretical spectra were compared with the available measured L$\beta _{2}$ satellite spectra. The peaks in the theoretical satellite spectra were identified as the experimentally reported satellites $\beta _{2}^{I}$ and $\beta _{2}^{II}$, which lie on the high-energy side of the L$\beta _{2}$ dipole line. [Preview Abstract] |
Thursday, May 18, 2006 2:54PM - 3:06PM |
N6.00008: High Precision Theory and Isotope Shifts for Li and Be+ Gordon Drake, Zong-Chao Yan In previsous work, we have obtained the most accurate results in the literature for the total energies and isotope shifts for the 2S - 2P and 2S - 3S transitions of lithium, The results provide a powerful new tool for the determination of nuclear charge radii for short-lived isotopes such as the halo nucleus $^{11}$Li [1]. The accuracy of these calculations is currently being increased by the use of larger basis sets in Hylleraas coordinates with multiple distance scales, and the introduction of multiple precision arithmetic. The calculations are also being extended to transitions and isotope shifts in Be+ for purposes of measuring nuclear charge radii in the isotopes of beryllium. As one example, our result for the Bethe logarithm for the 2S state of Be+ for the case of infinite nuclear mass is 2.97923(2) in units of $Z$-scaled Rydbergs. The present status of isotope shift measurements for light nuclei will be reviewed. \newline \newline [1] R. Sanchez et al., Phys. Rev. Lett. {\bf 73}, in press (2006), and earlier references therein. [Preview Abstract] |
Thursday, May 18, 2006 3:06PM - 3:18PM |
N6.00009: Precision Measurement of the 2$^{3}$S$_{1}$-2$^{3}$P$_{J}$ Transitions in $^{4}$He using an Optical Frequency Comb Daniel Farkas, Gerald Gabrielse One promising way to measure the fine structure constant $\alpha $ and test Quantum Electrodynamics in an atomic system is to measure the $^{4}$He fine structure splitting of the 2$^{3}$P level into the J=0,1,2 sublevels. We recently reported the most accurate experimental measurements of these intervals, with uncertainties of 500 Hz and 700 Hz for the small (2P$_{1}$-2P$_{2}$, 2.2 GHz) and large (2P$_{0}$-2P$_{1}$, 29.6 GHz) intervals, respectively [1]. Our approach uses saturated absorption laser spectroscopy at 1083 nm to excite metastable $^{4}$He atoms in a variable-pressure discharge cell to the 2P$_{J}$ states. Several changes to the experiment have improved our resolution by a factor of 5 to less than 100 Hz. Most significant, a new iodine frequency reference at 532 nm is 40 times more stable than an existing $^{3}$He reference. The stability of this reference is transferred to 1083 nm using an optical frequency comb. Simultaneously, the comb lets us accurately measure the optical frequencies of the 2S-2P$_{J}$ transitions with respect to the SI second. We present preliminary measurements of both the improved $^{4}$He 2P fine structure splittings and the 2S-2P$_{J}$ transitions using the iodine-stabilized frequency comb as the frequency reference for the experiment. Systematics and their limitations on accuracy are discussed. [1] T. Zelevinsky, D. Farkas, and G. Gabrielse, \textit{Phys. Rev. Lett}., \textbf{95}, (2005). [Preview Abstract] |
Thursday, May 18, 2006 3:18PM - 3:30PM |
N6.00010: Temperature Dependent Electronic and Vibrational Circular Dichroism of Carvone and Limonene Watheq Al-basheer, Jiangtao He, Prasad Polavarapu, Richard Pagni, Robert Compton Circular dichroism (CD) involves the differential absorption of right --and left-circularly polarized light by chiral molecules. Electronic circular dichroism (CD) and vibrational circular dichroism (VCD) spectra for both R- and S- enantiomers of optically active carvone (C$_{10}$H$_{14}$O) and limonene (C$_{10}$H$_{16})$ exhibit marked temperature dependences. The temperature dependence is due to the presence of both axial and equatorial conformations. Theoretical calculations, using density function theory (B3LYP with aug-cc-PVDZ basis set), show an equal magnitude but opposite \textit{sign} for the CD and VCD for the two conformers of each R- and S- enantiomer. The energy difference between the two conformers is also determined from these data (van t'Hoff plot) which show good agreement with values obtained by other spectroscopic methods. In addition, temperature dependent infrared absorption and Raman spectra for carvone and limonene will be used to further strengthen the conclusions from of the CD and VCD methods. [Preview Abstract] |
Thursday, May 18, 2006 3:30PM - 3:42PM |
N6.00011: Systematic Study of the $^{87}$Sr Clock Transition in an Optical Lattice Martin Boyd, Andrew Ludlow, Tanya Zelevinsky, Seth Foreman, Sebastian Blatt, Mark Notcutt, Tetsuya Ido, Jun Ye The $^{1}$S$_{0}-^{3}$P$_{0}$ transition in $^{87}$Sr is studied for the realization of an optical atomic clock, using $\mu $K atoms in a magic wavelength optical lattice [1]. The probe laser frequency is measured with an octave-spanning fs comb, which is referenced to a hydrogen maser (directly calibrated by the NIST primary Cs fountain clock) allowing high precision evaluation of potential systematic frequency shifts . By varying the lattice wavelength and trapping depth we find that the magic wavelength for the clock transition is 813.418(10) with a clock sensitivity to lattice deviations of $\sim $2 mHz/MHz for lattice intensities of 10 kW/cm$^{2}$. To explore the effect of atomic collisions on the clock frequency we varied the atomic density by a factor of 50 and did not find any shifts at the 3 x10$^{-14}$ level. Dependence of the clock transition on magnetic fields has been examined as the hyperfine interaction (I = 9/2), which provides the small transition moment for the doubly forbidden clock transition, also results in a differential g factor of the $^{3}$P$_{0}$ and $^{1}$S$_{0}$ levels. We will report the latest results of this optical clock system. [1] A.D. Ludlow et al., \textit{Phys Rev Lett} \textbf{96}, 033003 (2006). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700