Bulletin of the American Physical Society
Joint Fall 2012 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 57, Number 10
Thursday–Saturday, October 25–27, 2012; Lubbock, Texas
Session L1: Atomic, Molecular, and Optical Physics II |
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Chair: Walter Borst, Texas Tech University Room: Holiday Inn Towers University Room A |
Saturday, October 27, 2012 10:15AM - 10:27AM |
L1.00001: Calculating Properties of Finite Mass Atoms Steven Alexander, R.L. Coldwell Most atomic calculations assume that the mass of the nucleus is finite. If one is interested in evaluating atomic properties to high precision then this approximation cannot be made. We have developed a simple method that includes the kinetic energy of the nucleus into atomic calculations and does not increase the time or the complexity of these calculations. Our results for a variety of properties for several different atoms will illustrate some of the advantages of this method. [Preview Abstract] |
Saturday, October 27, 2012 10:27AM - 10:39AM |
L1.00002: Spectral Measurements of Low Temperature Plasma Formation at Atmospheric Pressure George Laity, Andrew Fierro, David Ryberg, Lynn Hatfield, Andreas Neuber This paper describes the study of the emission and re-absorption of ultraviolet (UV) and vacuum ultraviolet (VUV) radiation which is produced during the initial phases of plasma formation leading to electric field breakdown at atmospheric pressures. Specifically, there is interest in understanding the photon dynamics during the streamer to spark phase transition of plasma discharges which form less than 200 ns in millimeter-sized air gaps. Fast rise-time photo-multiplier measurements reveal that the earliest VUV emission occurs in the region near the anode, with emission points following streamer positions identified by fast intensified CCD imaging with fast electronic gating (\textless 3 ns). Electron densities and dissociation characteristics are estimated by using measurements of the HI Lyman-$\alpha $ (121.5 nm) Stark-broadened line profile as a function of distance from the anode. Successive measurements in pure N2 environments show a distinct two-step transition from radiative contributions of both the N2 second positive system in the UV (300 - 400 nm) and NI atomic structure in the VUV (120 - 180 nm) during the early plasma phase, to primarily VUV emission shortly after the plasma spark has formed. The observed emission dynamics are due to a combination of N2 dissociation into NI and radiation-less quenching of the N2 molecules. [Preview Abstract] |
Saturday, October 27, 2012 10:39AM - 10:51AM |
L1.00003: Entanglement of movable mirrors in a correlated emission laser Wenchao Ge, Hyunchul Nha, M. Suhail Zubairy We investigate the theory of entangling two macroscopic mechanical resonators (movable mirrors) through two-mode fields generated by a correlated emission laser source inside a doubly resonant cavity. The master equations and quantum Langevin equations are studied for the atomic system and field-mirror system respectively. We show that steady state entanglement of mirrors as well as two-mode fields can be obtained in the strong field-mirror interacting regime for the input laser frequencies both tuned at the anti-Stokes sidebands. The entanglement of movable mirrors and two-mode fields can be tuned on and off by the driving field which controls the atomic system in our case. Our scheme is able to entangle two macroscopic objects with state-of-art experiment. [Preview Abstract] |
Saturday, October 27, 2012 10:51AM - 11:03AM |
L1.00004: Comparative spectroscopic analysis of urinary calculi inhibition by \textit{Larrea Tridentata} infusion and NDGA chemical extract Felicia Manciu In the present comparative spectroscopic study we try to understand calcium oxalate kidney stone formation as well as its inhibition by using a traditional medicine approach with \textit{Larrea Tridentata }(LT) herbal extracts and nordihydroguaiaretic acid (NDGA), which is a chemical extract of the LT bush. The samples were synthesized without and with LT or NDGA using a simplified single diffusion gel growth technique. While the use of infusion from LT decreases the sizes of calcium oxalate crystals and also changes their structure from monohydrate for pure crystals to dihydrate for crystals grown with different amounts of inhibitor, both Raman and infrared absorption spectroscopic techniques, which are the methods of analysis employed in this work, reveal that NDGA is not responsible for the change in the morphology of calcium oxalate crystals and does not contribute significantly to the inhibition process. The presence of NDGA slightly affects the structure of the crystals by modifying the strength of the C-C bonds as seen in the Raman data. Also, the current infrared absorption results demonstrate the presence of NDGA in the samples through a vibrational line that corresponds to the double bond between carbon atoms of the ester group of NDGA. [Preview Abstract] |
Saturday, October 27, 2012 11:03AM - 11:15AM |
L1.00005: Sub-Wavelength Lithography Using Nitrogen-Vacancy Color Centers in Diamond Fahad Alghannam, Philip Hemmer, Zeyang Liao, Mohammad Al-Amri, M. Suhail Zubairy In classical optical lithography, resolution is limited to about half of the wavelength of the source used in the process. However, as we reach high frequencies (Deep UV or X-ray), several problems and difficulties occur. Over the last decade, several techniques were suggested to go beyond the classical limit. In 2010, Liao, Alamri, and Zubairy proposed a method using two lasers with different frequencies; one is used to induce Rabi oscillations between two states and the other is used to excite the ground state to a third state, thus writing the lithography pattern. In this presentation I will talk about an experimental approach to implement their method of sub-wavelength lithography using optical and magnetic properties of NV color centers in diamond. [Preview Abstract] |
Saturday, October 27, 2012 11:15AM - 11:27AM |
L1.00006: Quantum interference due to energy shifts and its effect on spontaneous emission Zheng-Hong Li, Da-Wei Wang, Hang Zheng, Shi-Yao Zhu, M. Suhail Zubairy The quantum interference in spontaneous emission is studied with the inclusion of counter rotating terms and energy shifts. The energy shifts come from the emission and then reabsorption of virtual photons as well as the real photon emission. We show that the quantum interference resulting from the energy shifts has significant influence on the effective decay rates of the two levels, even when the transition dipole elements are the same and the energy separation of the two levels is small. We also show that the energy shift has substantial influence on the spectrum emitted by the atom. The result is valid in the long time limit. The effect of the energy shift can be observed at the time scale of one over the atomic decay rate. [Preview Abstract] |
Saturday, October 27, 2012 11:27AM - 11:39AM |
L1.00007: Using a Microwave Resonant Cavity to Study Hydrogen Bonding at Phase Transition in H$_{2}$O and D$_{2}$O Jim Roberts, Jai Dahiya, S. Ghosh The resonant microwave cavity is a very sensitive device for detecting small changes in material properties as they are perturbed by temperature, electric and magnetic fields. In this laboratory all states of mater have studied with the resonant cavity, including the plasma state. In this paper we report on an experiment with water as it changes from liquid (disordered) to water ice (ordered) phase. In that hydrogen bonds are involved in this process, we are able to observe their behavior through the dielectric response of H$_{2}$O as it is cycled from solid to liquid. The transition through the densest state of water near 4$^{\circ}$C indicates that the structure of the water molecules in the ice phase at 0$^{\circ}$ C is less compact than that experienced at the most dense temperature of water. If we associate this density with the interaction of the hydrogen bonds, it can be postulated that the distribution of the structure in snowflakes is a consequence of random processes in sharing the hydrogen bonds as the system cycles from the ``disordered'' state to the more ordered state. In this work phase transition from liquid to solid and solid to liquid was studied for H$_{2}$O and D$_{2}$O. It was assumed that the bonding of the two molecules behave the same during the transition from ordered to disordered states and in the reverse transition for disordered to ordered states. The apparatus employed in this investigation is discussed briefly. [Preview Abstract] |
Saturday, October 27, 2012 11:39AM - 11:51AM |
L1.00008: Pulsed rotating supersonic source for merged molecular beams Les Sheffield, Mark Hickey, Vitaliy Krasovitskiy, Daya Rathnayaka, Igor Lyuksyutov, Dudley Herschbach We continue the characterization of a pulsed rotating supersonic beam source. The original device was described by M. Gupta and D. Herschbach, J. Phys. Chem. A \textbf{105}, 1626 (2001). The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, and a shutter gate eliminate the main handicap of the original device in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1--0.6 ms (depending on rotor speed) and containing $\sim$10$^{12}$ molecules at lab speeds as low as 35 m/s and $\sim$10$^{15}$ molecules at 400 m/s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O2, NO2, NH3, and SF6. For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when using two merged beams. By closely matching the beam speeds, very low \textit{relative} collision energies can be attained without making either beam very slow. [Preview Abstract] |
Saturday, October 27, 2012 11:51AM - 12:03PM |
L1.00009: Quantum heat engines, Fano Interference, Quantum Coherence and the Limits to photocell efficiency Philip Vetter In quantum heat engines, incident light excites electrons, which can then deliver useful work to a load. Radiatively induced quantum coherence can break detailed balance and yield lasing without inversion. It is claimed that it is possible to break detailed balance via quantum coherence, as in the case of lasing without inversion and the photo-Carnot quantum heat engine. Although in complete accord with the laws of thermodynamics, in principle, a quantum limit to photovoltaic operation can exceed the classical one, so that noise-induced quantum coherence, such as Fano coherence, enables us to break detailed balance and get more power out of a laser or photocell. [Preview Abstract] |
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