Bulletin of the American Physical Society
2006 Texas Section of the APS Joint Fall Meeting
Thursday–Saturday, October 5–7, 2006; Arlington, Texas
Session OT2: Other II |
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Chair: Don Kobe, University of North Texas Room: UT Arlington, University Center Palo Pinto |
Saturday, October 7, 2006 10:30AM - 10:42AM |
OT2.00001: Spectroscopic and \textit{ab initio} studies on the conformations and intramolecular hydrogen bonding of 2-indanol Abdulaziz A. Al-Saadi, Martin Wagner, Jaan Laane Infrared, Raman, ultraviolet absorption, and laser induced fluorescence (LIF) spectroscopies have been used along with theoretical calculations to study the structure and conformations of 2-indanol in its ground and excited electronic states. This molecule possesses an alcoholic OH group which can weakly hydrogen bond to its benzene ring. Both the calculations and the LIF of the jet-cooled molecules show that there are four stable conformers of this molecule which can interconnect through the ring-puckering and internal rotation vibrations. A two-dimensional potential energy surface was generated from the MP2 \textit{ab initio} calculations to depict the energetics of the conformational changes. The conformer with the intramolecular hydrogen bonding has the lowest energy by about 500 cm$^{-1}$ (1.4 kcal/mole) in the S$_{0}$ state. The ring-puckering frequencies for the different conformers range from 80 to 92 cm$^{-1}$. [Preview Abstract] |
Saturday, October 7, 2006 10:42AM - 10:54AM |
OT2.00002: Using Seismology to Map and Characterize the Glacial Bed in the Onset Region of Ice Stream D, West Antarctica Bridget McEwen Climate change has affected the flow of ice streams in the West Antarctic Ice Sheet (WAIS). In order to predict the future behavior of the ice streams in the WAIS, an understanding and characterization of the glacial bed is necessary. From analyzing the strength of the seismic reflection of the bed information can be extracted about the composition of the bed, such as the reflection coefficient. It had been determined, from previous research, that the bed under Ice Stream D is composed of glacial till. After analysis, my results further verify previous conclusions. Future research on Ice Stream D could further verify these findings and help predict flow behavior and how this will affect the drainage and the future of the WAIS. [Preview Abstract] |
Saturday, October 7, 2006 10:54AM - 11:06AM |
OT2.00003: Precision Measurement of the Microwave Properties of a Select Liquid Crystal James Roberts, Aman Anand, Jai Dahiya A cylindrical microwave resonant cavity in the TE$_{011 }$mode is used to study the microwave dielectric response of liquid crystal p-azoxyanisole at microwave frequencies. The dielectric behavior of this liquid crystal is studied as a function of frequency from 8.0 GHz to 10.2 GHz. The real and imaginary parts of the complex dielectric constant of this liquid crystal are calculated by using Slater's Perturbation Equations and the relaxation time is calculated using Debye's Equation for polar molecules. The microwave resonant cavity is interfaced to a computer and the dielectric relaxation data is taken using this computer interface. The frequency shift and the Q-changes of the signal are determined experimentally by using a computer interface. Manually tracking the markers can be very time consuming as well as erroneous sometimes. With the use of the computer interfaced resonant cavity this error is reduced dramatically and proves to be efficient. The computer also performs the calculations of the real and imaginary parts of the dielectric constant of the material under study and at the same time plots graphs of frequency shifts and Q-changes as a function of applied frequency for this experiment related to the microwave dielectric response of this liquid crystal. [Preview Abstract] |
Saturday, October 7, 2006 11:06AM - 11:18AM |
OT2.00004: Calculations of Energy Spectra of Quantum Systems Using the Feynman-Kac Path Integral Method James M. Rejcek, Nail G. Fazleev, John L. Fry A method for calculating the first few energy eigenvalues for quantum systems using the Feynman-Kac path integral is presented. The exact analytical solution of the Feynman-Kac path integral for the finite square well is presented and compared with numerical simulations approximated by random walk simulations on a discrete grid. Using the Laplace transform of the Feynman-Kac path integral and knowing the form of the eigenvalue expansion of the integral, it is possible to calculate the first few energy eigenvalues within an estimated uncertainty. The method provides exact values in the limit of infinitesimal step size and infinite time for the ground state. Improvements of the method have been explored and reasons for the deviations in past reported results are presented. [Preview Abstract] |
Saturday, October 7, 2006 11:18AM - 11:30AM |
OT2.00005: Vibrational Spectra, DFT Calculations, and the Unusual Structure and Vibrations of 1,3-Disilacylobutane Mohamed Z.M. Rishard, Richard M. Irwin, Jaan Laane The infrared and Raman spectra of 1,3-disilacyclobutane and its 1,1,3,3-d$_{4}$ isotopomer have been reexamined and partially reassigned based on DFT and \textit{ab initio} calculations. These calculations are in excellent agreement with the observed spectra in both frequency and intensity. They also demonstrate that this molecule has CH$_{2}$ wagging and twisting vibrations with frequencies below 1000 cm$^{-1}$, about 200 cm$^{-1}$ lower than expected. These unprecedented low values can be explained by the decreased slope in the potential energy curves for these vibrations as the sideways motions of the CH$_{2}$ groups result in attractive forces between the positively-charged hydrogens on the carbon atoms and the negatively charged hydrogens on the silicon atoms. The theoretical calculations also confirm the previous conclusions that the individual molecules in the vapor have C$_{2v}$ symmetry while in the solid the molecules become planar with D$_{2h}$ symmetry. [Preview Abstract] |
Saturday, October 7, 2006 11:30AM - 11:42AM |
OT2.00006: Role of analyticity and covariance in determining laws of mechanics John Fry, Zdzislaw Musielak, L.D. Swift We impose two postulates for state functions in our universe and use them to obtain dynamical equations of mechanics for isolated elementary particles. The first postulate is that the state function is analytic on its carrier space. The second postulate is that any equation defining the state function must be written in covariant form for the metric of its carrier space. This implies Wigner's definition of an elementary particle, which we adopt. Using a Minkowski metric we obtain equations for isolated elementary particles which resemble the Dirac and Klein-Gordon equations. We introduce a quantum action operator and observe that the state function must be an eigenfunction of the operator. It must have eigenvalue $\hbar $ to obtain the quantum theory of our universe. We identify the origin of Hamilton's principle for quantum systems as a consequence of the first two postulates and the definition of a particle. Dynamical equations in non-relativistic and classical limits will also be discussed. [Preview Abstract] |
Saturday, October 7, 2006 11:42AM - 11:54AM |
OT2.00007: Vibrational Spectra and Structure of Coumaran and Its Ring-Puckering Potential Energy Functions in the S$_{0}$ and S$_{1}(\pi $,$\pi $*) Electronic States Juan Yang, Martin Wagner, Katsuhiko Okuyama, Jaan Laane The far-infrared (IR), jet-cooled fluorescence excitation (FES), single vibronic level fluorescence (SVLF), and ultraviolet (UV) absorption spectra of coumaran have been recorded and analyzed. The assignment of those spectra has allowed a detailed energy map of both the S$_{0}$ and S$_{1}(\pi $,$\pi $*) electronic states of the ring-puckering ($\nu _{45})$ vibration to be determined. A one-dimensional potential energy function for the ring-puckering vibration very nicely predicts the experimentally determined energy level spacings for both electronic states. In the S$_{0}$ ground state the barrier to planarity is 154 cm$^{-1}$ and the puckering dihedral angle is 25\r{ }. In the S$_{1}(\pi $,$\pi $*) excited state the corresponding values are 34 cm$^{-1}$ and 14\r{ }. The decreased barrier in the electronic excited state results from decreased angle strain in the five-membered ring. [Preview Abstract] |
Saturday, October 7, 2006 11:54AM - 12:06PM |
OT2.00008: A New Line Representing Meson Masses and Angular Momenta: An Alternate Approach to Regge Lines Norman Redington, M.A.K. Lodhi Mesons within a given family are expected to lie on the so-called Regge lines with slope approximately 1.1 in the mass squared – angular momentum plane. This, in practice, is one of the tests of a successful meson model. In this work we show that instead of a set of Regge lines, only one line (with half the slope of Regge lines) is needed, representing the mass squared in increasing order. The uncertainty in this relation is statistically less than for conventional Regge lines. The slopes and intercepts of conventional Regge lines can be obtained from this new line in terms of a ``new number,'' which is related to masses of mesons. This new line is used to test the results for meson masses within various families as obtained from a five-dimensional wave equation, the Bethe-Salpeter equation, and the one-body Dirac equation. [Preview Abstract] |
Saturday, October 7, 2006 12:06PM - 12:18PM |
OT2.00009: Spectroscopic Studies and Ab Initio Calculations of 1,3-Benzodioxan in its S$_{0}$ and S$_{1}(\pi $,$\pi $*) Electronic States Kathleen McCann, Jaebum Choo, Martin Wagner, Jaan Laane Both the ground (S$_{0})$ and excited [S$_{1}(\pi $,$\pi $*)] states of 1,3-benzodioxan have been studied using molecular spectroscopy and theoretical calculations. Infrared, Raman, ultraviolet absorption, and laser-induced fluorescence (LIF) spectroscopies of the jet-cooled molecules were used to create energy maps for the vibrational and vibronic levels of the molecule, especially for the low-frequency vibrational modes which help to elucidate the conformational energetics of the molecule. The ring-bending, twisting, and flapping motions of the molecule provide the pathways for the conformational changes and were studied in considerable detail. The molecule is twisted with a high barrier to planarity of the equilibrium structure. [Preview Abstract] |
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