Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session W6: Optical Diagnostics and Characterization |
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Chair: F. Robicheaux, Auburn University Room: TELUS Convention Centre Macleod BC |
Saturday, June 9, 2007 8:00AM - 8:12AM |
W6.00001: Optical Absorption in Artificial Atoms Yiming Mi, Suichi Iwata Optical transitions in an artificial atom (AA) interacting with longitudinal optical phonons are studied theoretically, which can be solved exactly under the condition of finite number of carrier levels in the system. The linear optical properties are calculated, and the obtained results are compared with the ones of other theoretical model. Perhaps, the acquired theoretical results are of great interest and would get precise validations experimentally in near future. [Preview Abstract] |
Saturday, June 9, 2007 8:12AM - 8:24AM |
W6.00002: Energy relaxation and dephasing in CARS Svetlana Malinovskaya We use the adiabatic passage control scheme developed for the CARS spectroscopy to investigate the energy and phase relaxation as factors of the optical polarization decay. We show that in strong fields the dynamics of induced polarization via adiabatic passage is dependent on phase relaxation, and to less extent on energy relaxation for characteristic times close to pulse duration. We justify our conclusions with the dressed state dynamics analysis. [Preview Abstract] |
Saturday, June 9, 2007 8:24AM - 8:36AM |
W6.00003: Continuous Bremsstrahlung in Trojan atoms and molecules Matt Kalinski We present a fully relativistic approach to the electron radiation in Trojan atoms, atoms of hydrogen in circularly polarized electromagnetic field. Unlike for the normal scattering event the Bremsstrahlung is the continuous process and the cyclotronic radiation due to circular pseudo-scattering, when the electron is internally excited. Depending on the electromagnetic coupling order and the relativistic $v/c$ order the corrections can be interpreted as the native spontaneous emission and the Unruh-Davies effect. All contributions have their classical correspondence in equivalent parts of Lienard-Wiechert potentials. [Preview Abstract] |
Saturday, June 9, 2007 8:36AM - 8:48AM |
W6.00004: \textit{Escherichia coli} identification and strain discrimination using nanosecond laser-induced breakdown spectroscopy Steven Rehse, Jonathan Diedrich, Sunil Palchaudhuri Three strains of \textit{Escherichia coli}, one strain of black mold and one strain of \textit{Candida albicans} yeast have been analyzed by laser-induced breakdown spectroscopy (LIBS) using nanosecond laser pulses. All microorganisms were analyzed while still alive and with no sample preparation. Nineteen atomic and ionic emission lines have been identified in the spectrum, which is dominated by calcium, magnesium and sodium. A discriminant function analysis (DFA) has been used to discriminate between the bio-types and \textit{E. coli} strains. This is the first demonstration of the ability of the LIBS technique to differentiate between different strains of a single species. [Preview Abstract] |
Saturday, June 9, 2007 8:48AM - 9:00AM |
W6.00005: Recombination fluorescence in ultracold plasmas Scott Bergeson, Francis Robicheaux The expansion dynamics of ultracold neutral plasmas are determined by electron physics. Three-body recombination and electron-Rydberg scattering heat the plasma electrons at early times and drive the expansion. The details of these processes are well understood in weakly-coupled plasmas. However, these processes may proceed differently in strongly-coupled neutral systems. We present a study of recombination fluorescence in ultracold plasmas. At low densities, we find good agreement between theory and experiment. At higher densities, theory and experiment diverge. [Preview Abstract] |
Saturday, June 9, 2007 9:00AM - 9:12AM |
W6.00006: Ion Temperature and Expansion Velocity Measurements Through Fluorescence Imaging in Ultracold Neutral Plasmas Jose Castro, Hong Gao, Priya Gupta, Sampad Laha, Clayton Simien, Thomas Killian Imaging probes in Ultracold Neutral plasmas are used for studying strongly coupled systems. Doppler broadening of the light-scattering spectrum provides information on ion temperature and velocity. Absorption imaging shows Doppler broadening due to the combined effects of the radially directed expansion velocity and the random thermal motion of the ions. To distinguish these two quantities, fluorescence imaging of Ultracold Neutral Plasmas is used to produce a spatially-resolved spectrum that is Doppler-broadened due to thermal ion velocity and shifted due to ion expansion velocity. [Preview Abstract] |
Saturday, June 9, 2007 9:12AM - 9:24AM |
W6.00007: Trace Detection of Metastable He$_2$ Molecules in Superfluid Helium W.G. Rellergert, S.B. Cahn, A. Garvan, J.C. Hanson, J.A. Nikkel, D.N. McKinsey We present results on the detection and imaging of $\rm{He}_2$ triplet molecules in superfluid helium using laser induced fluorescence. A two photon transition at 905 nm results in the emission of a single detectable photon of shorter wavelength (640 nm). This cycling transition can be driven many times over the course of the molecule lifetime (13 s) resulting in good signal to noise. Control over the vibrational state of the molecule with the use of repumping lasers is demonstrated. Emission and absorption spectra in addition to images of the molecules obtained using the technique are shown. Detection of $\rm{He}_2$ molecules in liquid helium has potential applications in the detection of gamma rays, WIMP dark matter, and ultracold neutrons, as well as the three-dimensional imaging of fluid flow and vortices in superfluid helium. [Preview Abstract] |
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