Bulletin of the American Physical Society
2005 Joint Spring Meeting of the Texas Sections of the APS, AAPT, and Zone 13 SPS
Thursday–Saturday, March 3–5, 2005; Nacogdoches, TX
Session AA: APS I |
Hide Abstracts |
Sponsoring Units: TSF Chair: Robert Friedfeld Room: Science Building Room 323 |
Friday, March 4, 2005 1:30PM - 1:42PM |
AA.00001: Measurement of Index of Refraction using Low-Coherence Interferometry* Joshua Dickerson, Dhiraj Sardar The indices of refraction of various materials were measured in a Michelson interferometer using several low-coherence light sources and compared to the values measured by other methods. This measurement technique yielded a value of n = 1.47 for quartz and n=1.33 (660 nm) and n = 1.32 (940 nm) for water. The effects of dispersion in thick samples and other sources of error were also modeled and investigated. This technique will be used to measure the indices of refraction of various ocular tissues and compared with those available in the literature. \textbf{* This work was supported by the NSF sponsored Center for Biophotonics Science and Technology (CBST) at UC Davis. } \textbf{* The support by the UTSA Faculty Development Leave is duly acknowledged.} \textbf{* This work was also supported by NIH MARC-U*STAR Grant: GM07717.} [Preview Abstract] |
Friday, March 4, 2005 1:42PM - 1:54PM |
AA.00002: Fluorescence and Absorption Spectra and Potential Energy Surfaces of 1,3-Benzodioxole and Coumaran in Their S$_{0}$ and S$_{1}(\pi $,$\pi $*) States Katsuhiko Okuyama, Kevin Morris, Martin Wagner, Juan Yang, Jaan Laane The fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled molecules along with ultraviolet and far-infrared absorption spectra of the bicyclic molecules 1,3-benzodioxole and coumaran have been recorded. These spectra have allowed us to determine the two-dimensional potential energy surfaces for the ring-puckering and ring-flapping vibrations for the S$_{0}$ and S$_{1}(\pi $,$\pi $*) electronic states. Both molecules are bent with barriers to planarity in both their ground and excited states. The bent structures for coumaran result from --CH$_{2}$-CH$_{2}$- torsional forces while those for 1,3-benzodioxole are caused by the anomeric effect. [Preview Abstract] |
Friday, March 4, 2005 1:54PM - 2:06PM |
AA.00003: Experimental and \textit{Ab Initio} Spectra of 3-Methylindole in the Gas Phase Kathleen McCann, Amanda Combs, Daniel Autrey, Jaan Laane, Stacy Overman, George Thomas, Jr. 3-Methylindole (3MI), a structural model for the tryptophan side chain in proteins, has been investigated using vapor-phase infrared and Raman spectroscopy. The vapor Raman spectrum identifies the signature of the indolyl moiety free of intermolecular interaction. We have also utilized \textit{ab initio} calculations to refine and extend previous vibrational assignments. The present results provide an improved basis for assessing the dependence of the indolyl Raman signature on the local environment of the tryptophan side chain of proteins. The vapor Raman bands at 3506, 1585, 1409, 1349/1341 (Fermi doublet) and 881 cm$^{-1}$ differ greatly from their counterparts in the spectrum of the liquid and thus serve as spectral markers of the intermolecular interactions of the indolyl ring environment. The maximum value of the Fermi doublet intensity ratio (3.0) is observed for 3MI vapor, while the minimum value (0.43) is observed for 3MI in CHCl$_{3}$ solution. [Preview Abstract] |
Friday, March 4, 2005 2:06PM - 2:18PM |
AA.00004: Ultraviolet Cavity Ringdown Spectra of 2-Cyclohexen-1-one Mohamed Rishard, Jaebum Choo, Daniel Autrey, Jaan Laane, Stephen Drucker, Emily Giles The cavity ringdown spectrum of 2-cyclohexenone vapor has been recorded in the vicinity of the S$_{0}$ band, which is at 26 089.1 cm$^{-1}$. Several low-frequency fundamentals and overtones have been observed using this very sensitive technique which also allows even weak bands to be detected. The inversion of the six-membered ring ($\nu _{39})$ occurs at 99.0 cm$^{-1}$. With the help of far-infrared and Raman spectra, the frequencies for $\nu _{38}$ and $\nu _{37}$ have also been determined. The barrier to the inversion potential was found to be 1900$\pm $300 cm$^{-1}$, which is very different from previously reported values of 935 and 3379 cm$^{-1}$. Density functional calculations give a barrier of 2090 cm$^{-1}$ when the B3LYP/6-311+G(d,p) basis set is used. The frequencies calculated by the density functional methods agree very well with the experimental values obtained by liquid and vapor Raman spectra and also with the mid-IR experiments. Investigation of the T$_{1}$(n,$\pi ^{\ast })$ is currently underway. [Preview Abstract] |
Friday, March 4, 2005 2:18PM - 2:30PM |
AA.00005: Infrared, Raman, Ultraviolet Absorption, Fluorescence Excitation and Single Vibronic Level Fluorescence Spectra and Ab Initio Calculations of 1,4-Benzodioxan Juan Yang, Martin Wagner, Daniel Autrey, Jaan Laane The 1,4-benzodioxan molecule is expected to have a twisted C$_{2}$ structure due to the CH$_{2}$-CH$_{2}$ torsional interaction in the electronic ground state and MP2 calculations confirm that. Mid-infrared (IR) and Raman spectra of this molecule in both liquid and vapor phases were recorded and assigned. Density functional theory (DFT) calculations were carried out to predict the vibrational frequencies. The calculated frequencies, after proper scaling, agreed very well with the experimental values. Ultraviolet (UV) absorption, fluorescence excitation (FES) and single vibronic level fluorescence (SVLF) spectra were also obtained and assigned. From those spectra several energy levels of the ring-bending and ring-twisting vibrations in both the electronic ground and excited states were determined. [Preview Abstract] |
Friday, March 4, 2005 2:30PM - 2:42PM |
AA.00006: Femtosecond CARS on organic molecules Dmitry Pestov, Miaochan Zhi, Robert Murawski, Alexei Sokolov, Nikolai Kalugin, Yuri Rostovtsev, Zoe Sariyanni, Vladimir Sautenkov, Marlan Scully Quantum coherence dynamics on vibrational transitions in organic molecules is studied by means of femtosecond Coherent Anti-Stokes Raman Scattering (CARS) technique. CARS signal profiles for high-frequency Raman transitions in methanol and ethanol, as representative simple organic substances, are obtained. The detailed, good-visibility profiles, spanning six decades in signal magnitude, show clear low-frequency oscillations, attributed to quantum beats, and make it possible to extract decoherence time constants. Non-trivial dependence of these constants on methanol/ethanol concentration in water solution is observed. Coherent response from a saturated solution of dipicolinic acid, which has much more complex molecular structure, is also demonstrated. [Preview Abstract] |
Friday, March 4, 2005 2:42PM - 3:06PM |
AA.00007: BREAK - AA
|
Friday, March 4, 2005 3:06PM - 3:18PM |
AA.00008: Switchable Diffraction Gratings Holographically Formed in Polymer-Dispersed Liquid Crystal Cells using He-Ne Laser Robert Ramsey, Suresh Sharma We report on the holographic formation of switchable diffractive transmission gratings in polymer-dispersed liquid crystal cells by using the 632.8 nm wavelength of He-Ne laser. We present results for the micro-structure, diffraction efficiency and switching characteristics for gratings utilizing E8 liquid crystal along with monomers having varying values of functionality and chemical makeup. For monomers having high values of functionality we note a large increase in diffraction efficiency up to 67\% while at the same time an increase in the switching fields required to have a switchable grating are 8 MV/m. [Preview Abstract] |
Friday, March 4, 2005 3:18PM - 3:30PM |
AA.00009: UV-Ozone Oxidation of ultra thin Ru layers ChangDuk Lim, Vaishali Ukirde, Oliver Chyan, Mohamed El Bouanani Ruthenium and its oxides and nitrides are potential candidates for number of advanced applications in Silicon based semiconductor technology such as metal-based gate electrodes and diffusion barriers for copper interconnects. This is due to their good thermal stability, low resistivity, suitable work function and diffusion barrier properties. Physico-chemical and electrical properties of Ru oxides are intimately dependent on the oxide preparation method mainly due to the resulting microstructure, oxidation state and impurities/contaminants. 5 to 7 nm Ru films were deposited on Si and SiO2 substrates by DC magnetron sputtering in Ar atmosphere. The films were then exposed to UV/Ozone radiation and oxygen at room temperature for a duration ranging from 15 min to 60 min. In-situ X-ray photoelectron spectroscopy (XPS) is used to investigate Ru oxidation rate and the bonding environment. A comparison with Ru oxide prepared via reactive DC sputtering in an Ar/O2 mixture will be presented. [Preview Abstract] |
Friday, March 4, 2005 3:30PM - 3:42PM |
AA.00010: Interfacial stability of RuO2 on HfxSi1-xO2/Si Vaishali Ukirde, Changduk Lim, Manuel Quevedo-Lopez, Mohamed El Bouanani Alternative metal-based gate electrodes are currently under consideration as a replacement of Poly-Si gates. Metal gates are required to maintain scaling and performance of future CMOS devices. Ru based compounds are potential gate electrode candidates for future metal-oxide-semiconductor (MOS) devices. RuO2, with thickness of 500A were deposited on HfxSi1-xO2/Si structures by DC sputtering. These structures were annealed in flowing N2 atmosphere at temperatures ranging from 800C to 1000C. The thermal stability and interfacial diffusion and reaction of RuO2 on HfxSi1-xO2/Si gate dielectric were investigated using Rutherford Backscattering Spectrometry (RBS) and SEM. An overview of RuO2/ HfxSi1-xO2/Si interface integrity and pinhole formation issues will be presented. [Preview Abstract] |
Friday, March 4, 2005 3:42PM - 3:54PM |
AA.00011: Drell-Yan Physics at Fermilab: Past and Future L. Donald Isenhower The study of the Drell-Yan process has yielded a number of important results that have improved our understanding of the light quark sea of the proton. Fermilab E866/NuSea performed the first measurements of the absolute Drell-Yan cross section in proton-proton collisions over a broad kinematic region, and the most extensive study to date of the Drell-Yan cross section in proton-deuterium collisions. It also made the first measurement of this cross section ratio of proton-proton to proton-deuterium collisions over a large kinematic range, allowing the extraction of the ratio of anti-down to anti-up quark in the proton. After reviewing E866 results and their contributions to various areas, such as structure function calculations, the plans for E906, which will utilize the Fermilab Main Injector will be discussed. The lower energy of the Main Injector provides a higher Drell-Yan cross section, allowing the extension of to higher Bjorken-x where E866 hints of possible continued departure from unity of the d/u anti-quark ratio. Other important physics questions that E906 will pursue will also be discussed. [Preview Abstract] |
Friday, March 4, 2005 3:54PM - 4:06PM |
AA.00012: An Investigation of the Canis Major Dwarf Galaxy William Lee Powell Jr., Ron Wilhelm, Amy Westfall, Adam Lauchner, Abel Diaz Martin et al. (2004) uncovered evidence for a remnant dwarf galaxy in Canis Major. Martin et al. discovered an overdensity of M-giant stars using 2MASS colors. The spatial distribution of the M-giants indicate that Canis Major is an extended, and likely disrupted, group of stars that that are centered at a distance moduli of (m-M) = 15.8 and extending over roughly 30 degrees. This discovery is not without controversy. Momany et al. (2004) found that the proper motions of the M-giants in the direction of Canis Major are consistent with the thick disk of the Galaxy, but also found modeled number densities for these stars that are consistent with the warp and flaring of the outer disk of our Galaxy. This led Momany et al. to the conclusion that Martin et al. were actually observing the outer warp of our Galaxy. We made a photometric survey to find candidates of the Canis Major galaxy which could belong to the horizontal branch of the galaxy. We then obtained spectroscopy of these stars in order to determine luminosity class, metal abundance and distance estimates. The goal was to find a group of horizontal branch stars, as is expected for an old population, in the Canis Major dwarf. This would have ramifications for our understanding of the thick disk population in our Galaxy. [Preview Abstract] |
Friday, March 4, 2005 4:06PM - 4:18PM |
AA.00013: Possible Applications and Limitations of Multi-Walled Carbon Nanotubes to Solar Energy Conversion Robert Friedfeld Recent experimental work has shown that multi-walled carbon nanotubes (MWCNT) can behave like receiving antennas for visible light.[1] One possible application for this newly observed behavior for carbon nanotubes might be for solar energy conversion. Pontential applications and limitations of this technology to solar energy conversion will be discussed. \begin{enumerate} \item Y. Wang et. al., Applied Physics Letters, Vol. 85, No. 13, 2004. \end{enumerate} [Preview Abstract] |
Friday, March 4, 2005 4:18PM - 4:30PM |
AA.00014: Study of the acridine labelled short DNA-duplexes by means of rotational depolarization of fluorescence Alexey Chugreev, Alexander Ogrodnik Dye-DNA compounds have attracted much interest in the quest of potentialities~for cancer treatment and serve as very versatile workbenches for exploring the basics of molecular wire technology. For such studies exact positioning of a dye within the sequence is crucial, and can be achieved by a flexible covalent link. Proper intercalation of such a dye can be tested by monitoring the inclination angle of the transition moment with the spinning axis of short DNA double helices by means of rotational depolarization of the dye fluorescence.~ For 9-amino-6-chloro-2-methoxyacridine attached with a tetramethylene linker at an abasic L-threoninol site we found this angle to be larger than 70 degrees. Since the fluorescence is quantitatively quenched in sequences with~guanine~neighboring the linker site, these results suggest~complete intercalation of the dye. [Preview Abstract] |
Friday, March 4, 2005 4:30PM - 4:42PM |
AA.00015: Oxidation of Hafnium as studied by X-ray Photoelectron Spectroscopy A. Chourasia, Richard Miller Thin films of hafnium were deposited on stainless steel substrate at various temperatures in an oxygen atmosphere. The technique of X-ray photoelectron spectroscopy was used to study the oxidation of hafnium. The zirconium anode (energy = 2042.4 eV) was used as the source of excitation. The 3d core levels of hafnium (energy $\sim $1660 eV) and the x-ray excited MNN Auger region of hafnium were investigated. The Auger parameter was determined from the core levels and the main peak in the Auger region. The data are correlated with the oxidation of hafnium as a function of the temperature. The thickness of the oxide films were determined by using the QUASES software. The dependence of the film thickness on the substrate temperature will be presented. [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