| Virtual Environments Overview |
Apr-2009 |
49 pages |
| Authors:
Susan U Stucky; Ben Shaw; Wendy Ark; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
 | This report provides a research-based schema called A Framework for Designing with Virtual World Technologies. It is shown how, by using this framework, virtual world technologies can be used to radically transform how intelligence analysts encounter data, frame their stories, and review their analyses with both their customers and other analysts. The report explores what analysts can accomplish by doing some of their work in environments that can be created ... |
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| Spin Coherence and Magnetization Transport in Nanometer-Scale Structures |
31 MAR 2005 |
27 pages |
| Authors:
Barbara Jones; Donald Eigler; Andreas Heinrich; Antonio Castro-Neto; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Highlights of the full reporting period include the construction of a custom-built low-temperature high magnetic field STM with ultra high vacuum sample preparation, the first of its kind. Key experimental results were obtained in STM studies of Kondo lattice and in behavior of Kondo effect in magnetic fields. IBM achieved its milestone of demonstrating single-atom spin-flip spectroscopy, published in Science (2004). IBM finalized its work on the spectroscopic properties of ... |
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| Final Report on Contract N00014-92-C-0173 (Office of Naval Research) |
10 JAN 2001 |
293 pages |
| Authors:
Michael Philpott; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| The primary objective of the proposal was the design and execution of computer experiments designed to provide the first detailed picture of the dynamics of adsorption of ions and small neutrals on metal electrode surfaces as well as any concomitant changes in the electric double layer. Using molecular dynamic (MD) and Monte Carlo (MC) statistical techniques video movies of these simulations became an integral part of the effort, since visual ... |
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| The Stanford IBM Management of Multiple Information Systems (TSIMMIS)- IBM Almaden Research Center |
MAR 2000 |
112 pages |
| Authors:
Allen W. Luniewski; Laura Haas; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| This report is a compilation of a summary of the research work and publications produced as a result of information systems management projects. This project attacked two problems of relevance to the Intelligent Integration of Information (I3) program: the classification of semi-structured data to allow ingestion of that data into a data management systems, and the creation of "wrapper" technology to allow integration of multiple, disparate, ... |
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| Electronic Applications of Magnetic Resonance Force Microscopy |
JUL 96 |
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| Authors:
Daniel Rugar; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| High Temperature Nonlinear Optical Chromophores and Polymers |
31 MAR 96 |
65 pages |
| Authors:
Robert D. Miller; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| We have developed a thermal protocol for the evaluation of NLO chromophores for very high temperature electro-optical applications with poled polymers. This protocol has been demonstrated to have significant predictive utility for EO applications. We have demonstrated that while chromophore thermal instability and nonlinearity are linked, this relationship is not inviolable. Certain thermally stable NLO chromophores have been incorporated into polyimide derivatives either by flexible tether connections or by direct ... |
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| Symposium on Molecular Tribology Held in Anaheim, California on 4-6 April 1995 |
21 MAR 96 |
45 pages |
| Authors:
Peter Schmidt; Mathew Mate; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| This contract provided funding for a Symposium entitled 'Molecular Tribology' which was part of the American Chemical Society National Meeting held in Anaheim, California, April 4-6, 1995. Attendees, about 40 per session, came from many diverse disciplines - chemistry, physics, engineering, etc. - but all had a common interest in the molecular origins of tribology. Thirty four papers were presented on the following topics: (1) atomic-scale simulations of tribology phenomena; ... |
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| Study and Development of Polymeric Photorefractive Materials |
21 NOV 95 |
33 pages |
| Authors:
Donald M. Burland; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| The research program summarized here involved the development of new organic photorefractive polymers, improvements of our understanding of the fundamental phenomena that govern photorefractivity in these polymer systems and an optimization of the materials properties for practical device applications. Of particular emphasis were systems that might be of use as optical limiters in eye and sensor protection devices. At the time that the work supported under this contract began, photorefractive ... |
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| Reasoning Under Uncertainty |
26 JAN 95 |
10 pages |
| Authors:
Joseph Y. Halpern; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| This report summarizes the research performed under this contract. The research can he divided into four areas: (1) Computing degrees of belief, (2) Reasoning about knowledge and communication, (3) Nonmonotonic reasoning, and (4) Belief change. Topic (1) is concerned with how an agent such as a doctor should assign degrees of belief to events such as Tom has hepatitis given a large knowledge base of first-order and statistical information (such ... |
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| Scanning Tunneling Microscopy and Low Energy Electron Microscopy of Metal Overlayers on Metal Surfaces |
95 |
47 pages |
| Authors:
Robert J. Wilson; David D. Chambliss; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Thin metal films are of ever increasing importance as the scale of devices shrinks. In order to provide new insight into the atomic details of metal film structure and the nanoscopic details of magnetic domains, efforts were made to study thin metal films on tungsten single crystals using both scanning tunneling microscopy (STM) and spin polarized low energy electron microscopy (SPLEEM). Difficulties were encountered with the as-delivered SPLEEM instrument which ... |
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| Screening of Charged Electrodes in Aqueous Electrolytes |
29 AUG 94 |
12 pages |
| Authors:
Michael R. Philpott; James N. Glosli; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Molecular dynamics simulations are used to demonstrate for the first time that systems about 4 nm thick containing 1200 to 1600 water molecules and NaC1 at 1M to 3M concentrations exhibit the main components of electric double layers at charged metal surfaces. In particular for the system chosen there are regions clearly identifiable as a bulk electrolyte zone, a diffuse layer that screens the charge on the electrode and a ... |
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| Molecular Dynamics Study of Aqueous Electrolyte Solutions Near a Structured Sphere |
22 AUG 94 |
14 pages |
| Authors:
Sheng-Bai Zhu; Michael R. Philpott; James N. Glosli; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Molecular dynamics studies of water and ions around a charged small compact globular object are described. The hypothetical molecular ion C(--) sub 60 is used as the globular model. It is found that the cesium cation is in physical contact on the spherical surface much of the time with an incomplete hydration shell. The chloride ion spends part of the time in a solvent-separated adsorption configuration and part of the ... |
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| Comparison of Water Models in Simple Electric Double Layers |
09 AUG 94 |
30 pages |
| Authors:
Sheng-Bai Zhu; Michael R. Philpott; James N. Glosli; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| The three bulk water models (SPCE, TIP4P and ST2) are compared in molecular dynamics simulations of electric double layers consisting of a monovalent ion (Na(+) or Cl(-)), water as solvent, and a flat metal electrode. The goal is to identify features of the double layer that are sensitive to the model and those that are not. The simulations are done with zero external field and one non-zero applied field. All ... |
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| Time Domain Spectral Hole-Burning Storage |
02 MAY 94 |
18 pages |
| Authors:
Michael Jefferson; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| This work achieved several substantial results. A highly stabilized laser system suitable for many detailed studies of data storage phenomena was constructed and made to work. This laser was essential for the investigations which followed. Using the stabilized laser, a real time correlator was demonstrated, which correctly identified all occurances of a test sequence imbedded in random data. This correlator is the first demonstration of the use of phase modulation ... |
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| Molecular Dynamics Computer Simulations of Charged Metal Electrode- Aqueous Electrolyte Interfaces |
18 FEB 94 |
29 pages |
| Authors:
Michael R. Philpott; James N. Glosli; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| When two different substances are joined, material flows across the interface (sometimes imperceptibly almost) until the chemical potentials of the component species are equalized. When the substances are solid or liquid and some of the chemical species are charged, then the interface develops a net electrical polarization due to the formation of an electric double layer. The main goal of this program of study is to give a molecular basis ... |
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| Infrared Spectroelectrochemical Study of Cyanide Adsorption and Reactions at Platinum Electrodes in Aqueous Perchlorate Electrolyte |
18 FEB 94 |
36 pages |
| Authors:
Kevin Ashley; Daniel L. Feldheim; Diane B. Parry; Mahesh G. Samant; Michael R. Philpott; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| In situ infrared (IR) spectroelectrochemistry is used to investigate the behavior of cyanide (CN) at polycrystalline platinum surfaces in aqueous perchlorate (CLO4(-) electrolyte, IR spectroelectrochemical data reveal the existence of a number of surface, as well as solution, cyanide species in the interfacial region. Within the double-layer potential region, there is IR evidence for several forms of absorbed cyanide. When the potential is made sufficiently positive, cyanide is oxidized to ... |
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| Image Description and 3-D Reconstruction from Image Trajectories of Rotational Motion. |
SEP 1993 |
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| Authors:
H. S. Sawhney; J. Oliensis; A. R. Hanson; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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 | This paper presents a new technique for reconstructing the 3-D structure and motion of a scene undergoing relative rotational motion with respect to the camera. Given image correspondences of point features tracked over many frames, a two-stage technique for reconstruction is presented. First, a grouping algorithm that exploits spatio-temporal constraints of the common motion to achieve a reliable description of discrete point correspondences are curved trajectories (general conics in the ... |
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| Molecular Dynamics Modeling of Electric Double Layer |
14 APR 93 |
19 pages |
| Authors:
James N. Glosli; Michael R. Philpott; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Constant temperature molecular dynamics calculations of a simple model of a charged metal electrode immersed in electrolyte show the following features known to exist experimentally: incipience of a compact layer, formation of a diffuse layer, presence of highly oriented water layer next to the metal, penetration of nominally diffuse layer species into inner Helmholtz region, ion pair formation between contact adsorbed ion and diffuse layer ion. All these effects emerge ... |
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| Molecular Dynamics Modeling of Electric Double Layers with Spectroscopic Applications |
14 APR 93 |
8 pages |
| Authors:
M. R. Philpott; J. N. Glosli; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Molecular dynamics is used to model the structure and dynamics of electric double layers at a charged metal surface and to ask questions of spectroscopic interest. In particular: What is the molecular basis for changing the position of the outer Helmholtz plane (OHP) thereby tuning the electric field across the inner layer? Another topic is the microscopic basis of modulation spectroscopies like SNIFTIRS. Our MD simulations of an immersed electrode ... |
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| In Situ Fourier Transform Infrared Spectroscopic Study of Bisulfate and Sulfate Adsorption on Gold, With and Without the Underpotential Deposition of Copper |
14 APR 93 |
46 pages |
| Authors:
Diane B. Parry; Mahesh G. Samant; H. Seki; Michael R. Philpott; Kevin Ashley; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| In situ surface infrared (IR) spectroelectrochemistry is used to investigate the adsorption of sulfate (SO4(2-)) and bisulfate (HSO(4-)) ions on polycrystalline gold surfaces in sodium sulfate and sulfuric acid, and also during copper underpotential deposition in sulfuric acid medium. In sodium sulfate solution, IR peaks due to surface sulfate and bisulfate are observed at potentials within the double-layer region on gold, and the ratio of IR peak intensities for sulfate ... |
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| Fast Multipole Method in Simulations of Aqueous Systems |
14 APR 93 |
14 pages |
| Authors:
James N. Glosli; Michael R. Philpott; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| The fast multipole method (fmm) for calculating electric fields developed by Greengard and Rokhlin (J. Comp. Phys. 73, 325(1987)), has been implemented specifically for molecular dynamics simulations of electrochemical problems including boundary conditions associated with metal electrodes. This order N (number of charged particles) algorithm, is known to be computationally much more efficient than direct or Ewald sum methods (order N 2) for systems with as few as one thousand ... |
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| Photon Antibunching in the Fluorescence of a Single Dye Molecule Trapped in a Solid |
08 JUN 92 |
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| Authors:
Th. Basche; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| The correlation between fluorescence photons emitted by an optically pumped single molecule of pentacene in a p-terphenyl host has been investigated at short times. The correlation function shows photon antibunching, an unique feature of nonclassical radiation field, which decreases if two molecules rather than one are pumped at the same time. The peculiarities of the correlation function for a three-level molecule are discussed and the theoretical description outlined. Single-molecule spectroscopy ... |
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| Observation and Study of the Photorefractive Effect in Doped Nonlinear Polymers, |
22 MAY 1992 |
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| Authors:
D. M. Burland; S. Ducharme; W. E. Moerner; J. C. Scott; C. A. Walsh; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Many applications of photorefractivity have been proposed: a virtually unlimited array of image processing techniques including phase conjugation and novelty filtering, simulations of neural networks and associative memories, and high density efficient holographic optical storage. Until very recently, all materials showing the photorefractive effect have been inorganic crystals. A problem currently impeding the wide-spread exploitation of the photorefractive effect has been the fact that inorganic materials exhibiting the effect tend ... |
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| Frequency - Domain Measurements of Spectral Hole Patterns Burned with Phase - Coherent Pulses, |
22 MAY 1992 |
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| Authors:
C. M. Jefferson; Alfred J. Meixner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Several investigations have shown that in some systems stimulated photon echoes may be obtained over times much longer than the excited state relaxation T(1). It has been claimed that the mechanism for this anomalously long storage time is the formation of a frequency dependent modulation of the ground state population which persists because of spectral hole-burning. Such a population grating produced by coherent multipulse excitation and spectral hole-burning has been ... |
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| Squeezed Optical Solitons, |
APR 1992 |
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| Authors:
Robert M. Shelby; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| An optical fiber is a dispersive nonlinear waveguide. Short pulses in single-mode fibers broaden temporally due to the dispersion in the group velocity, and broaden spectrally due to the intensity-dependence of the index of refraction of fused silica which leads to self-phase modulation. Classical optical solitons avoid this distortion because the phase shifts due to these two effects are made to balance each other. This balance is achieved by the ... |
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| Pyrolysis and Laser Ablation of Plasma-Polymerized Fluorocarbon Films: Effects of Gold Particles. |
1992 |
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| Authors:
William R. Creasy; Jeffrey A. Zimmerman; Wolfgang Jacob; Eric Kay; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Plasma-polymerized fluorocarbon (PPFC) films were analyzed by thermogravimetric analysis (TGA), direct pyrolysis/mass spectrometry, and laser-ablation/electron-impact mass spectrometry. Fourier transform mass spectrometry was used to detect products. The films were made by plasma polymerizing tetrafluoroethylene in an argon plasma. Two types of films were studied: with and without fine gold particles incorporated in the PPFC films. TGA showed that gold-containing films decompose more rapidly and at lower temperature with increasing gold ... |
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| Optical Spectra of Fullerenes: C60 a New Amorphous Semiconductor. |
1992 |
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| Authors:
Andrew Skumanich; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| The optical absorption spectra for thin films of sublimed C(60) and C(70) are presented. Both transmission spectroscopy and photothermal deflection spectroscopy are used to obtain the spectrum over a wide energy range (0.4 to 6.2 eV) for the same film. The optical gap varies for the different fullerenes. The value for C(60) is approximately equal to 1.6 eV and the corresponding transition appears to be optically forbidden given the weakness ... |
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| Two-Beam Coupling Measurements of Grating Phase in a Photorefractive Polymer |
25 NOV 91 |
|
| Authors:
C. A. Walsh; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| We investigate in detail the grating properties of a recently discovered organic photorefractive polymer as a function of electric field using two-beam coupling. We present measurements of index and absorption grating phase relative to the intensity interference pattern as well as the amplitude of both the absorption and index gratings. We find that in low electric fields, a weak in-phase grating (possible photochromic) and the low electro-optic coefficient prevent observation ... |
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| Optical Spectra and Kinetics of Single Impurity Molecules in a Polymer: Spectral Diffusion and Persistent Spectral Hole-Burning |
07 NOV 91 |
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| Authors:
W. P. Ambrose; T. Basche; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Using high efficiency fluorescence excitation techniques, optical spectra of single impurity molecules of perylene in a poly(ethylene) matrix can be obtained at 1.5 K. Analysis of such spectra show a variety of spectral diffusion effects, including fast resonance frequency changes on the 1-100 MHz scale which lead to a range of apparent linewidths, as well as discontinuous jumps in the resonance frequency of 10-1000 MHz on a longer time scale. ... |
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| Optical Modification of a Single Impurity Molecule in a Solid |
17 OCT 91 |
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| Authors:
T. Basche; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| The possibility of obtaining information about solids on a truly microscopic scale has stimulated several advances in the optical detection and spectroscopy of single impurity centers in solids. For the system composed of pentacene impurity molecules in the crystal terphenyl, absorption and fluorescence excitation studies at liquid helium temperatures have led to direct observations of the lifetime-limited homogeneous linewidth of a single pentacene molecule as well as surprising observation of ... |
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| Single Molecule Spectral Diffusion in a Solid Detected Via Fluorescence Spectroscopy |
15 OCT 91 |
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| Authors:
W. P. Ambrose; T. Basche; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Recent advances in fluorescence excitation spectroscopy have produced significant increases in detection sensitivity for single performance molecules in crystals of p-terphenyl at low temperatures. With the increased signal to noise ratio, we have observed two classes of pentacene behavior. While some pentacene defects have fixed, lifetime limited Lorentzian excitation line shapes (7.8 MHz FWHM), other pentacene defects exhibit spontaneous shifts in resonance frequency of up to 100 MHz Residence times ... |
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| Interpreting IR Difference Spectra |
26 SEP 91 |
35 pages |
| Authors:
Diane B. Parry; Mahesh G. Samant; Owen R. Melroy; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| From the evaluation of sample difference spectra based on Gaussian model peaks with known peak characteristics, it is shown that interpretation of some parameters from difference spectra, resulting from the ratioing or subtraction of a poor background spectra, may be inaccurate or misleading. Difference spectra of this type are commonly observed using techniques such as subtractively normalized interfacial Fourier transform infrared spectroscopy, SNIFTIRS, electrochemically modulated infrared reflectance spectroscopy, EMIRS, or ... |
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| Photorefractivity in Doped Nonlinear Organic Polymers |
07 AUG 91 |
|
| Authors:
W. E. Moerner; C. Walsh; J. C. Scott; S. Ducharme; D. M. Burland; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| This paper describes the properties of a new class of materials exhibiting the photorefractive effect, doped nonlinear organic polymers. Photorefraction (at 647.1 nm) was established by a combination of hologram erasability, correlation with photoconductivity and electro-optic response, and enhancement by external fields in numerous samples of two nonlinear epoxy materials doped with hole transport agents based on p-diethylaminobenzaldehyde- diphenyl hydrazone (DEH). Diffraction efficiencies up to 0.1% were observed at bias ... |
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| Detection and Spectroscopy of Single Pentacene Molecules in a p- Terphenyl Crystal by Means of Fluorescence Excitation |
22 JUL 91 |
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| Authors:
W. P. Ambrose; T. Basche; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Recent advances in fluorescence excitation spectroscopy with high efficiency have produced greatly improved optical spectra for the first electronic transition of individual single molecules of pentacene in p-terphenyl crystals at low temperatures (1.5 to 10 K). Two classes of single molecules behavior are observed: class I molecules have time independent resonance frequencies, and class II molecules show a diffusive motion among several resonant frequencies with time which we term spectral ... |
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| Electrochemical Contact Adsorption Site Changes Driven by Field and Charge Fact and Theory |
19 APR 91 |
19 pages |
| Authors:
Michael R. Philpott; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| When solvated anions like chloride or cyanide adsorb on metal electrodes from aqueous media they lost part of their solvation shell yielding a direct metal-ion bond. For certain anions this 'contact' adsorption can occur even when the electrode carries net negative charge. On the basis of classical electrochemical measurements and deductive reasoning using simple models, electrochemists have evolved a detailed 'standard model' of the disposition of ions, water, and organics ... |
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| Bonding Geometry and Bonding Character of Thiocyanate Adsorbed on A ag(100) |
07 MAR 91 |
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| Authors:
Gianfranco Pacchioni; Francesc Illas; Michael R. Philpott; Paul S. Bagus; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Finding a Single Molecule in a Haystack: Laser Spectroscopy of Solids from Sqrt. N to N = 1 |
02 JAN 91 |
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| Authors:
W. E. Moerner; W. P. Ambrose; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Recent progress in the optical detection and spectroscopy of single ions in vacuum confined in electromagnetic traps has led to novel measurements that further our understanding of quantum physics. For example, various workers have achieved direct measurement of quantum jumps, Doppler sidebands, and other fundamental phenomena such as ion crystallization of ions in vacuum trapped by electromagnetic fields. By using laser induced fluorescence and a novel hydrodynamically-focused flow to confine ... |
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| Effect of Intense and Prolonged 248 nm Pulsed-Laser Irradiation on the Properties of Ultraviolet-Grade Fused Silica |
91 |
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| Authors:
Wing P. Leung; Murli Kulkarni; Doug Krajnovich; Andrew C. Tam; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| We have studied changes in the absorption, temperature, ultraviolet (UV) spectrum, birefringence, and surface profile of various high-purity "UV- grade" fused silica samples during KrF excimer laser irradiation at 400 mJ/sq cm and 300 Hz and up to a total of 60000000 pulses. All samples exhibit permanent and irreversible changes in the spectroscopic and physical properties. Some samples show a partial "self-annealing" behavior during the irradiation in which the absorption ... |
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| Investigations of the Epitaxial Growth and Characterization of High Perfection Magnetic Thin Films |
91 |
43 pages |
| Authors:
R. F. Farrow; S. S. Parkin; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Methods of preparing high-perfection single crystalline films of 3d elements (including Fe, Co) and magnetic rare earths on semiconducting GaAs substrates have been investigated. The use of seed layers of Fe or Co (a few monolayers thick), deposited onto GaAs(001), followed by a Ag(001) film, provided a suitable template for Fe epitaxy. This method avoided interfacial chemical reactions between Fe and the semiconductor, at the expense of introducing coherency strain ... |
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| Effect of Intense and Prolonged 248 nm Pulsed-Laser Irradiation on the Properties of Ultraviolet-Grade Fused Silica. |
1991 |
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| Authors:
Wing P. Leung; Murli Kulkarni; Doug Krajnovich; Andrew C. Tam; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Changes have been studied in the absorption, temperature, ultraviolet (UV) spectrum, birefringence, and surface profile of various high-purity "UV-grade" fused silica samples during KrF excimer laser irradiation at 400 mJ/sq cm and 300 Hz and up to a total of 60 million pulses. Permanent and irreversible changes in the spectroscopic and physical properties are exhibited in all samples. During the irradiation some samples show a partial "self-annealing" behavior in which ... |
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| Comment on 'Single Pentacene Molecules Detected by Fluorescence Excitation in a P-Terphenyl Crystal' |
10 DEC 90 |
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| Authors:
W. E. Moerner; W. P. Ambrose; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Using highly efficient Fluorescence excitation spectroscopy of individual pentacene molecular impurities in p-terphenyl crystals, we have observed that some pentacene defects exhibit spontaneous spectral jumps in their resonance frequency at 1.5 K, with a jump rate independent of laser power. In addition, the low-power limiting linewidth for single pentacene absorbers reaches the lifetime limit of 7.8 MHz at 1.5 K. |
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| Observation of the Photorefractive Effect in a Polymer |
10 DEC 90 |
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| Authors:
S. Ducharme; J. C. Scott; R. J. Twieg; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| We report the observation of the photorefractive effect in an amorphous electro-optic material, the nonlinear polymer bisphenol A diglycidyl ether 4-nitro-1,2,phenylenediamine (bisA-NPDA) make photoconductive by doping with the hole transport agent diethylaminobenzaldehyde-diphenyl hydrazone (DEH). The gratings formed exhibit: dynamic writing and erasure, strong electric field dependence, polarization anisotropy, diffraction efficiencies up to 6 x 10 -5 in a 356 micron film, and large estimated photorefractive space-charge fields. Continuous realignment of ... |
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| Conference on Theoretical Aspects of Reasoning about Knowledge |
03 DEC 90 |
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| Authors:
Moshe Y. Vardi; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| The Third Conference on Theoretical Aspects of Reasoning about Knowledge was held at the Asilomar Conference Center in Pacific Grove. Seventy- nine papers, covering aspects of reasoning about knowledge in artificial intelligence, computer science, economics, and philosophy, were submitted in response to a call for papers. The program committee considered all the papers carefully; at least three and usually four committee members read each paper. In the end, nineteen papers ... |
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| Observation of Spectral Diffusion in Crystals Using Single Impurity Molecules |
31 OCT 90 |
|
| Authors:
W. P. Ambrose; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Early measurements of the optical absorption spectrum of a single impurity molecule in a solid at low temperatures, while intriguing, nevertheless produced insufficient signal-to-noise ratio for the observation of new physical effects. Recent advances in high-efficiency fluorescence excitation spectroscopy have removed this obstacle. For the case of pentacene molecules inp-terphenyl, both stable as well as spectrally diffusing single molecules can be observed. |
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| Phase-Sensitive Optical Detection of Ballistic Phonon Pulses Using Frequency-Modulation Spectroscopy and Persistent Spectral Holes |
04 MAY 90 |
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| Authors:
W. P. Ambrose; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Using laser frequency-modulation spectroscopy and persistent spectral holes, time-resolved phase-sensitive probing of ballistic phonons generated by an absorbed Nd:YAG laser pulse is accomplished in the interior of a solid sample. Measurement of the time dependence and sign of a propagating stress- strain field is illustrated using spectral holes in the in-homogeneously broadened 607 nm color center absorption in x-irradiated NaF at liquid-helium temperatures. By examining the dependence of the observed ... |
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| Ultrasensitive Laser Spectroscopy in Solids: Statistical Fine Structure and Single-Molecule Detection |
28 MAR 90 |
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| Authors:
W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| Detailed studies of the low-temperature inhomogeneously broadened 0-0 S(1)-S(0) electronic transition of pentacene dopant molecules in p-terphenyl crystals have produced two novel observations which open up a new regime for ultra-sensitive laser spectroscopy in solids. The first result, direct detection of intrinsic static absorption fine structure on a megaHertzs scale, called statistical fine structure, arises from number fluctuations in the spectral density of absorbers which scale as the square root ... |
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| Intracavity Frequency Doubling of a Nd:YAG Laser with an Organic Nonlinear Optical Crystal |
13 MAR 90 |
|
| Authors:
Stephen Ducharme; W. P. Risk; W. E. Moerner; Victor Y. Lee; R. J. Twieg; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| We have demonstrated intracavity second harmonic generation of green 532 nm light in a quasi-cw 1064 nm Nd:YAG laser using organic nonlinear optical crystals of DAN (4-(N,N-dimethylamino)-3-acetamidonitrobenzene) immersed in index matching fluid contained in an antireflection-coated cuvette. This technique permits crystals to be used directly from solution growth without polishing or antireflection coating them. Up to 0.56 mW peak power of 532 nm light was generated from 2.3 W of ... |
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| Soluble Polysilanes: A New Class of Radiation Sensitive O2-Rie Resistant Polymers for Use in Microlithography |
12 MAR 90 |
|
| Authors:
R. D. Miller; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| This report describes the progress in the synthesis, characterization and spectroscopy of soluble polysilanes and germanes. It includes polymer structural studies, theoretical investigations of electronic structure and mechanistic studies of the photodecomposition. It also describes the potential of these materials as polymeric photoconductors, and as new materials for microlithography. The initial work on the nonlinear optical characteristics of these materials is also included. Keywords: Polysilane; Synthesis; Spectroscopy; Photochemistry applications. (sdw) ... |
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| Covalent and Ionic Contributions to the Bonding of Atomic and Molecular Adsorbates on Metal Surfaces: A Cluster Model Approach |
19 FEB 90 |
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| Authors:
Gianfranco Pacchioni; Paul Bagus; M. R. Philpott; C. J. Nelin; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
|
| The molecular cluster model approach for the description of processes at surface is presented. It involves using finite clusters which contain surface atoms interacting with atomic or molecular adsorbates. Accurate ab initio wavefunctions can be obtained for the clusters and thus makes it possible to describe the bonding in terms that are familiar for molecular systems. The adsorbate-substrate interaction can be analyzed by means of new techniques developed to characterize ... |
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| Temperature Dependence of Photon-Gated Persistent Spectral Hole-Burning for the meso-tetra-p-tolyl-Zn-Tetrabenzoporphyrin/Chloroform System in poly(Methylmethacrylate) |
06 NOV 89 |
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| Authors:
W. P. Ambrose; W. E. Moerner; IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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| Persistent spectral hole-burning has been utilized as both a tool for studying relaxation processes in amorphous solids and as a means for possibly achieving high-density frequency-domain optical storage. Persistent spectral holes are formed in inhomogeneously broadened absorption lines when a photoinduced change occurs in the subset of absorbers that are in resonance with a narrowband laser beam. If the photoreacted centers do not absorb at the original wavelength, a dip ... |
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