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 M7: Undergraduate Session |
Hide Abstracts |
Chair: Charles Conover, Colby College Room: Terrace |
Thursday, June 7, 2012 8:00AM - 8:30AM |
M7.00001: LeRoy Apker Award Lecture: Strong-field dissociation dynamics of NO$^{2+}$: A multiphoton electronic or vibrational excitation? Invited Speaker: Bethany Jochim A 3-D momentum imaging technique is employed to study intense ultrafast laser-induced dissociation of a metastable NO$^{2+}$ beam. We focus on N$^{+ }$+ O$^{+}$ coincidences and explore possible dissociation pathways using estimates of the initial vibrational population and transition rates between the X $^{2}\Sigma ^{+ }$and A $^{2}\Pi $ states together with our measured kinetic energy release and angular distribution spectra. Our analysis suggests that lower intensity pulses ($<$10$^{15}$ W/cm$^{2})$ drive perpendicular transitions between these states. Higher intensity pulses ($\sim $10$^{16}$ W/cm$^{2})$, on the other hand, yield a prominent contribution from molecules breaking parallel to the polarization. An intriguing possibility is that this feature is due to a two photon permanent dipole transition to the vibrational continuum of the X $^{2}\Sigma ^{+}$ state, $i.e.$, a multiphoton vibrational excitation involving only the electronic ground state. The results of our time-dependent Schr\"{o}dinger equation calculations comparing the probabilities of this type of pathway and competing electronic transitions will be presented. [Preview Abstract] |
Thursday, June 7, 2012 8:30AM - 8:45AM |
M7.00002: Calculations of Hyperfine Antihydrogen Spectroscopy Patrick Donnan, Francis Robicheaux In 2011, the Antihydrogen Laser PHysics Apparatus (ALPHA) Collaboration reported trapped antihydrogen atoms in the ground state,\footnote{G.B. Andresen \textsl{et al}, Nature Physics \textbf{7}, 558 (2011).} placing spectroscopic measurements of antihydrogen within experimental reach. We present simulations for hyperfine spectroscopy of antihydrogen contained in a Penning-Malmberg trap. The trap used in the simulations approximates the magnetic fields present in the ALPHA trap. Using the Landau-Zener approximation we compute the transition rates for antihydrogen from a trapped, low-field-seeking state to an untrapped, high-field-seeking state when resonant microwaves are applied. We present results for each of the two low-field-seeking states. We show that resonances occur near the trap minimum, and that the rates are sufficiently high to distinguish spin-flipped antihydrogen atoms from cosmic noise counts. We determine that a pulsed application of the microwaves is optimal and show the feasibility of microwave spectroscopy, which can also serve as a detection tool for trapped antihydrogen atoms. We also report on the feasibility of laser cooling antihydrogen for future spectroscopic measurements. [Preview Abstract] |
Thursday, June 7, 2012 8:45AM - 9:00AM |
M7.00003: Empirical Model for Total Internal Reflection (TIR) from Highly Turbid Media Kashika Goyal, Miao Dong, Bradley Worth, Lalit Bali, Samir Bali Recently we introduced a new empirical model for total internal reflection (TIR) from a highly turbid medium [W. Calhoun, et al, \emph{Opt. Lett.} {\bf 35}, 1224-1226 (2010); \emph{ibid} {\bf 36}, 3172 (2011)]. The key feature of our model is that it incorporates into Fresnel theory the effect of angle-dependent penetration of the incident light into the medium. Here we show that the TIR data is, for the first time, well described by a model which has no extraneous fitting parameters. As a further check we use our model to extract the particle size for a highly turbid aqueous solution of monodisperse polystyrene microspheres of known size. Next we apply our model to a first in-situ measurement of average particle size in a widely used intravenous human nutrient [Preview Abstract] |
Thursday, June 7, 2012 9:00AM - 9:15AM |
M7.00004: Modeling Quantum Spin Dynamics in an Ultracold Gas B.J. Land, C.D. Hamley, C.S. Gerving, T.M. Hoang, M.L.B. Anquez, M.S. Chapman A recent experiment in our lab focuses on investigating spin dynamics in the quantum regime, where mean field approaches fail. Previous theoretical models for the quantum dynamical evolution of a spin-1 Bose-Einstein condensate do not include the effects of atomic loss that is unavoidable in experiment. Here, we present results of different loss models including a fully quantum calculation of this complicated many body system using a Monte-Carlo approach. We compare the results of these methods to recent experimental measurements and obtain good agreement. [Preview Abstract] |
Thursday, June 7, 2012 9:15AM - 9:30AM |
M7.00005: Revisiting Pound-Drever-Hall frequency stabilization in the radio-frequency domain Chelsea Liekhus-Schmaltz, James Martin By revisiting Pound-Drever-Hall locking as a method for stabilizing rf oscillators, we have developed two new laser stabilization methods and an undergraduate lab exploring the technique. In the first stabilization scheme a tunable rf source (stabilized using Pound-Drever-Hall locking) phase modulates an injection locked diode laser. The length of an optical cavity can be locked to one of the adjustable sidebands of this laser, which stabilizes a second laser [1]. The second scheme is a version of rf beat note locking with one frequency modulated laser. The rf heterodyne signal can be mixed with an rf tunable source and a Pound-Drever-Hall error signal generated from reflection off an rf cavity can stabilize one of the original lasers. By changing the tunable frequency, the locked laser frequency can be changed. The stability and tunability of both stabilization methods are established by observing the hyperfine components of the $^{87}$Rb $5P_{3/2}-5D_{5/2}$ transition in a vapor cell. Finally, an undergraduate lab [2] was developed that consists of locking a voltage-controlled-oscillator to a copper resonating cavity using Pound-Drever-Hall locking. By working at lower frequencies, the technique can be understood in more detail.\\[4pt] [1] arxiv/1109.0338\\[0pt] [2] arxiv/1108.0960 [Preview Abstract] |
Thursday, June 7, 2012 9:30AM - 9:45AM |
M7.00006: A new $^{3}$He-$^{129}$Xe Co-magnetometer using a Ramsey measurement sequence and Rb-K magnetometer for spin detection Aaron Kabcenell, Iannis Kominis, Michael Romalis Noble gas co-magnetometers have been used for many precision measurements, but their sensitivity is still very far from fundamental limits. We are exploring a new approach for operation of a $^{3}$He-$^{129}$Xe co-magnetometer that uses a sensitive Rb-K magnetometer as a spin detector. By placing the noble gas atoms inside the magnetometer cell we can increase their magnetic signal using the Fermi-contact interaction, representing a gain of nearly 500 for $^{129}$Xe, and achieve nearly quantum-noise limited detection of nuclear spins. In order to take advantage of the long coherence times of $^{3}$He and$^{129}$Xe, the precession measurement is based on the Ramsey method of separated oscillatory fields and will be performed in an alkali-metal-free volume. The gas is then transported to the spin detector using techniques developed for remote NMR detection. The sensitivity of this approach is estimated to be on the order of 10$^{-13}$ Hz/day$^{1/2}$, making it several orders of magnitude more sensitive than the best existing co-magnetometers. We are currently performing tests of the Ramsey measurement method and the sensitivity of the spin detector. [Preview Abstract] |
Thursday, June 7, 2012 9:45AM - 10:00AM |
M7.00007: Investigating Electronic Properties and Bound-Bound Transitions in the Negative Ion of Lanthanum Daniel Matyas, Adam Lebovitz, Kirsten Liebl, Daniel Gibson, Walter Wesley The electronic structure and correlation of the electrons in the negative ion of lanthanum have been investigated using laser photodetachment spectroscopy. The ions were photodetached by an infrared laser beam that crossed the ion beam path and the resulting neutral atom signal was measured as the photon energy was scanned. Ten resonance peaks were observed between 0.290eV - 0.510 eV. Some resonance peaks are identified as being due to bound-bound electric dipole transitions by comparing to theoretical calculations [1]. The negative ion of lanthanum is extraordinary because it is only the third atomic negative ion demonstrated to have bound-bound electric dipole transitions and it has several bound states of opposite parity. These properties have led to the proposal of the negative ion of lanthanum as a good candidate for laser cooling [1].\\[4pt] [1] S.M. O'Malley and D.R. Beck, \textit{Phys. Rev. A} \textbf{81}, 032503 (2010). [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