Bulletin of the American Physical Society
74th Annual Meeting of the Southeastern Section
Volume 52, Number 13
Thursday–Saturday, November 8–10, 2007; Nashville, Tennessee
Session JC: Atomic and Molecular Physics |
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Room: Scarritt-Bennett Center Laskey B |
Friday, November 9, 2007 1:30PM - 1:42PM |
JC.00001: Photodetachment spectroscopy near the lowest threshold of the O$^{-}$ ion John N. Yukich, Robert H. Mohr Numerous experiments have investigated photodetachment spectroscopy in a magnetic field at the $^{2}$P$_{3/2 }\to \quad ^{3}$P$_{2}$ threshold of ions such as S$^{-}$ and O$^{-}$. The threshold energy is known as the atom's \textit{electron affinity}. In this work we have investigated detachment at the lowest-lying threshold for the O$^{-}$ ion, the $^{2}$P$_{1/2 }\to \quad ^{3}$P$_{2}$ threshold. Our experimental apparatus includes a Penning ion trap in which the ions are created, trapped and stored, and a single-mode, amplified diode laser. Our observations yield a quantitative measurement for the threshold energy and an indirect measurement for the spin-orbit splitting of the ion. [Preview Abstract] |
Friday, November 9, 2007 1:42PM - 1:54PM |
JC.00002: The Excited States of Nitric Acid: Recent Results Paul Helminger, Douglas T. Petkie, Ivan Medvedev, Frank C. De Lucia Because nitric acid is an important molecular species in the ozone cycle in the upper atmosphere, it has been the subject of many studies in both the infrared and microwave regions of the spectrum. Microwave studies of the rotational spectrum of nitric acid in excited vibration states contribute both to a better understanding of this fundamental molecule and to the construction of accurate spectral maps for infrared remote sensing. We have recently completed work on the rotational spectrum of the interacting v6+v7 and v8+v9 states of nitric acid. The results of this work will be discussed. Our recent progress on the interacting v3 and v4 states will also be presented. Our microwave studies of the rotational spectrum of nitric acid now includes work on all of the excited states below 1250 cm$^{-1}$ in energy as well as the v2 state at 1700 cm$^{-1}$. [Preview Abstract] |
Friday, November 9, 2007 1:54PM - 2:06PM |
JC.00003: Acoustic Desorption from a Room Temperature Ionic Liquid. Peter Harris, Eugene Tracy, William Cooke We report on the acoustic desorption of ions from the surface of a room temperature ionic liquid (RTIL) under vacuum. Our RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate, remains a stable liquid at extremely low pressures ($<$10$^{-9}$ torr). Using the 2$^{nd}$ harmonic of a Nd:YAG laser, 2ns pulse time, we ablate the backside of a metal foil, generating an acoustic pulse that propagates through the foil, desorbing ions off the surface of the RTIL. We determine the m/q of desorbed ions via time of flight (TOF) measurements from an imaging micro-channel plate detector. We detect both positive and negative ion species, depending on the extraction and acceleration voltages. Our TOF spectra demonstrate our acoustic pulses are of short duration ($<$20ns), generating mass spectra with good temporal resolution ($<$40ns FWHM @ t=9000ns), that are stable and reproducible. We discuss the variation of desorbed ion yield as a function of acoustic pulse strength, metal foil properties and extraction fields. [Preview Abstract] |
Friday, November 9, 2007 2:06PM - 2:18PM |
JC.00004: Laser-induced breakdown spectroscopy for measurement of fuel/oxygen mixing in combustion Matthew Dackman, J.W.L. Lewis, Ying-Ling Chen, Lei Shi Laser-induced breakdown spectroscopy (LIBS) is applied for measurement of C-O equivalence ratios and mixing in a methane/oxygen flame. A nominal 10-nanosecond Q-switched Nd:YAG laser is used to effect a cascade-type optical breakdown in the flame, which is projected above a pre-mixed McKenna burner. Atomic and ionic carbon and oxygen spectra are used to verify the combustion equivalence ratios in the range of 0.5 to 2.0. Emission spectra are obtained separately from the near ultraviolet (vicinity of 250nm) and from the visible (vicinity of 430nm) using gated array detectors. Emission data are obtained over a range of sub-microsecond delay times following the laser pulse. The ultraviolet lines exhibit significantly larger signal-to-noise/background ratios, but the visible lines possess greater relative intensity. Implications of these results are discussed for local measurements of fuel-oxidizer ratios for both atmospheric pressure and high pressure combustion. [Preview Abstract] |
Friday, November 9, 2007 2:18PM - 2:30PM |
JC.00005: The two-electron molecule ion, H3+, in a magnetic field Nicolais Guevara-Leon The lowest electronic states of the two-electron molecular system, H3+, in linear parallel configuration in a magnetic field is investigated. Evolution of the ground state with a magnetic field increase is studied and it is shown that the quantum numbers of the state of the lowest total energy ground state depend on the magnetic field strength. [Preview Abstract] |
Friday, November 9, 2007 2:30PM - 2:42PM |
JC.00006: ABSTRACT WITHDRAWN |
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