| A Long-Term Comparison of GPS Carrierphase Frequency Transfer and Two-Way Satellite Time/Frequency Transfer |
01 JAN 2007 |
15 pages |
| Authors:
Christine Hackman; Judah Levine; Thomas E. Parker; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
 | GPS carrier-phase frequency transfer (GPSCPFT) and two-way satellite time and frequency transfer (TWSTFT) were performed along three transatlantic links over the 6-month period 29 January 31 July 2006. The GPSCPFT and TWSTFT results were subtracted in order to estimate the combined uncertainty of the methods. The frequency values obtained from GPSCPFT and TWSTFT agreed at 1.8 to 3.8 10(exp-16) RMS for averaging times of 30 d, with no single value ... |
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| Progress Report and Proposed Work for Year 2. ONR Contract N00014-89-J- 1227 |
AUG 95 |
13 pages |
| Authors:
John L. Hall; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| The focus of the work is the development of precision laser techniques and their application to physical problems of outstanding scientific interest, including laser frequency stabilization at/below the Hertz level, cold atomic 'fountains', optical frequency standards, ultra-resolution spectroscopy, measurement of optical frequencies, and advanced tests of physical principles. The main thrusts in the near future are to complete our frequency measurements of the stabilized Nd laser, to exploit our new ... |
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| Semiconductor Deposition and Etching Interactions of Laser-Generated Translationally Hot Atoms and Radicals |
31 DEC 94 |
32 pages |
| Authors:
Stephen R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Laser vaporization of cryogenic films is employed to produce translationally fast atoms and radicals, and these kinetic-energy-enhanced species are used for studies of semiconductor etching; the results are important for the basic physics of electronics materials processing. Recent accomplishments include (1) production of a novel source of kinetic-energy- enhanced beams of Cl(2), Cl, and F atoms by laser vaporization, (2) observation of substantial enhancement of the etching rate and sustained ... |
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| Collision-Induced Neutral Loss Reactions of Molecular Dications |
19 NOV 1993 |
11 pages |
| Authors:
Stephen D. Price; Michelle Manning; Stephen R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| Collision-induced neutral loss reactions are observed to be a major product channel for reactions of CF3(2+), SF4(2+), SF3(2+), and SF2(2+) with the rare gases at 49 eV laboratory collision energy. This reactivity, which involves the formation of doubly charged molecular daughter ions, differs markedly from that observed for other molecular dications. The double charged product ion yield is largest for systems in which charge transfer does not compete effectively with ... |
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| Applications of the Photorefractive Effect and Damage Induced Effects in Fibers |
26 MAR 92 |
17 pages |
| Authors:
Dana Z. Anderson; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| One aspect of this work concerns the processes of self-organized second-harmonic generation in fibers. We have experimentally investigated the nature of grating formation in the glass fibers and found it to be reversible. That is, a grating can be repetitively written, erased, and re-written. We have also shown that the grating erasure follows a power-law time dependence and explain the dependence as a consequence of the transverse mode structure of ... |
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| Optical and Electrical Characteristics of the Cathode Fall |
JAN 92 |
30 pages |
| Authors:
Z. Lj. Petrovic; A. V. Phelps; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| Experiments with hydrogen discharges dominated by the cathode fall show that (a) these discharges are unstable for wide ranges of current and circuit resistance, (b) increasing the circuit capacitance expanded the region of instabilities to lower currents, (c) lateral constrictions of the discharge occur over a much more limited range of currents and pressures than do oscillations, (d) laser-induced photoelectron pulses produce damped oscillations for discharge currents below those at ... |
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| State-Resolved Dynamics of Ion-Molecule Collisions in a Flowing Afterglow |
16 DEC 91 |
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| Authors:
Stephen R. Leone; Veronica M. Bierbaum; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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 | The dynamics of ion-molecule collision processes have been explored in flowing afterglow-drift and single collision instruments using laser-induced fluorescence and Doppler resolved laser probing. The velocity distributions of Ba+ drifted in both helium and argon buffer gases have been determined and compared with theoretical predictions. Ion mobilities and parallel and perpendicular temperatures have been measured as a function of field strength; in addition, the first experimental determination of skewness parameters ... |
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| Laser Probing of the Kinetics and Dynamics of III - V Semiconductor Growth |
31 JAN 91 |
7 pages |
| Authors:
Stephen R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Work is carried out on the dynamics of Ga, In, and As scattering, sticking, and desorption from silicon single crystals using laser induced fluorescence probing of the Ga and In atoms and As dimer gas phase species. Desorption kinetics are used to probe the InAs and GaAs heterostructures on silicon and the islanding behavior that occurs for the mixed systems. It is observed that islands form readily when In or ... |
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| Laser Measurements of State-Resolved Ga and In Atom Sticking and Desorption on Metal and Semiconductor Surfaces |
31 JAN 90 |
18 pages |
| Authors:
Stephen R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| Work is carried out on the dynamics of Gallium, Indium, and Arsenic scattering, Sticking, and desorption from silicon single crystals using laser probing of the Ga and In atoms and As dimer gas phase species. Results have been obtained for the binding energies of Ga and In on silicon. Structural patterns of Ga on silicon at various coverages have been determined by LEED studies. Results have been obtained for the ... |
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| International Conference on Multiphoton Processes (4th) Held in Boulder, Colorado on July 13-17, 1987: Program and Abstracts |
JUL 88 |
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| Authors:
JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Multiphoton Processes (Cambridge Studies in Modern Optics: 8) |
88 |
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| Authors:
Stephen J. Smith; Peter L. Knight; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Partial contents: Investigations of the role of ponderomotive forces in ATI using subpicosecond laser pulses; Electron energy spectra in high intensity multiphoton ionization; Limiting cases of excess photon ionization; Above threshold ionization of atomic hydrogen: Angular distribution of photoelectrons; Continuum transitions in multiphoton ionization and electron scattering; Discussion of the role of many electron motions in multiphoton ionization and excitation; The stepwise process of doubly charged barium ions formation; Quasiclassical ... |
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| Group IIA Metastable Collision Complexes: Spectroscopy and Behavior in Intense Radiation Fields |
18 SEP 87 |
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| Authors:
J. Cooper; J. Coutts; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| This report describes work addressing the problems of collisional induced oscillator strength and energy transfer from metastable states in Group IIA alkaline earth metal atoms. The quenching of CA 3PJ states when perturbed by rare was atom collisions is investigated and such quenching is found to be negligable. The CA 1D2 state, however shows considerable collisional induced effects. Calculations have been performed which show that collision cross- sections for transfer ... |
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| Solar Oscillations and Convective Flows as Probes of Structure in the Subphotosphere |
15 APR 87 |
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| Authors:
Juri Toomre; Katharine B. Gebbie; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Application of inverse theory to the observation of high-degree five- minute solar oscillations has led to the detection of horizontal flows below the solar surface that are a combination of solar rotation and giant convection cells. The distinctive displacements in the centroids of the ridges evident in the power diagrams of the oscillations from one observing day to the next arise from different patterns of giant cells being rotated into ... |
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| Precision Atomic Beam Spectroscopy Using Stabilized Lasers |
30 JUN 85 |
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| Authors:
John L. Hall; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| The goal of our work has been to investigate a few well-chosen effects in laser spectroscopy under clean experimental conditions which facilitate a sharp and meaningful contact with theory. The initially-defined task was to study large pulse-area effects in single upward transitions from metastable atoms in a fast, monovelocity Ne* beam. It proved possible as well to investigate multiple-pulse transitions on a cw basis. Ramsey fringe resonance signatures were clearly ... |
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| Vibrational Energy Disposal in Reactive and Inelastic Collisions of H(D) + HCl(DC1) at 1-3 eV |
01 NOV 84 |
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| Authors:
C. A. Wight; F. Magnotta; S. R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Vibrational energy disposal due to reactive exchange and unreactive translational-to-vibrational excitation in hyperthermal collisions of H + HCl and deuterated analogs is investigated by the excimer laser photolysis/infrared fluorescence technique. In the H + DCl system the excitation of DCl vibration increases from an energy efficiency of 4% to 9% as the initial H atom energy is increased from 1.4 to 3.1 eV. Only about 2% of the available energy ... |
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| State-Resolved Molecular Reaction Dynamics |
84 |
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| Authors:
S. R. Leone; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Gas phase molecular reaction dynamics is a mature field, but one that continues to offer exciting new perspectives on the fundamental nature of chemical transformations. This review focuses on recent experimental investigations in state-resolved molecular reaction dynamics, involving primarily work carried out from 1980 to 1983. A common trend is toward investigations that involve a higher degree of sophistication to learn about geometrical and orientation effects, bimodal state distributions that ... |
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| A Study of Secular and Tidal Tilt in Wyoming and Utah |
01 NOV 1983 |
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| Authors:
J. Levine; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| During the period covered by this report, we drilled ten holes at five sites in Yellowstone National Park. We designed and constructed equipment for recording tilt data at the sites and for transmitting the data to our laboratory in Boulder. We installed instruments at three of the sites and began recording data to our laboratory in Boulder. We installed instruments at three of the sites and began recording data. At ... |
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| The JILA (Joint Institute for Laboratory Astrophysics) Portable Absolute Gravity Apparatus |
AUG 1983 |
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| Authors:
J. E. Faller; Y. G. Guo; J. Gschwind; T. M. Niebauer; R. L. Rinker; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| We have developed a new and highly portable absolute gravity apparatus based on the principles of free-fall laser interferometry. A primary concern over the past several years has been the detection, understanding, and elimination of systematic errors. In the Spring of 1982, we used this instrument to carry out a survey at twelve sited in the United States. Over a period of eight weeks, the instrument was driven a distance ... |
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| Theory of Stimulated Raman Scattering with Broad-Band Lasers |
18 DEC 1981 |
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| Authors:
M. G. Raymer; J. Mostowski; J. L. Carlsten; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Transport of Resonance Excitation in Na Vapor Excited by White Light |
04 JUN 1981 |
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| Authors:
T. Fujimoto; A. V. Phelps; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Multi-Term Boltzmann Analysis of Electrons in N2 |
MAY 1981 |
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| Authors:
L. C. Pitchford; A. V. Phelps; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| A multi-term spherical harmonic expansion method was previously developed for the numerical solution of the Boltzmann transport equation in the context of electron swarm analysis. Here, the method is used to investigate the validity of the more usual two-term spherical harmonic expansion in nitrogen. The multi-term method has also been used to study the effects of ionization and anisotropic cross-sections. Studies are given of the convergence of swarm parameters using ... |
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| Measurement of Electron Excitation of the a 1 delta g State of 02 Using the Swarm Technique |
MAY 1981 |
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| Authors:
K. Tachibana; A. V. Phelps; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| Measurements have been made of electron excitation coefficients for the a 1 delta g metastable state of O2. The measurements were made in mixtures 1 and 5% O2 in Ar for mean electron energies between about 0.9 and 4 eV. The measured excitation coefficients are about 30% above predictions for 1% O2 and about 30% below predictions for 5% O2. The measured rate coefficient for quenching of the O2(a1 delta ... |
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| Research in Laser Processes. |
15 JAN 1981 |
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| Authors:
A. V. Phelps; A. C. Gallagher; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Measurements at very high rare gas densities have yielded the contribution of trimer molecules, e.g., NaXe2, to the absorption and stimulated emission continuum of metal vapor-rare gas excimers. Attempts to obtain a sufficiently high electron and excited state temperature in a pulsed discharge in high pressure metal vapor-rare gas mixtures were unsuccessful because of the approach of the system to local thermodynamic equilibrium and the limited peak electrical energy available. ... |
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| Nonradiative Transport of Atomic Excitation in Na Vapor, |
12 Dec 1980 |
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| Authors:
Arthur G Zajonc; A V Phelps; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Direct Detection of the Product Vibrational-State Distribution in the Associative Detachment Reaction Cl(-)+H yields HCl(v)+e, |
06 FEB 1980 |
|
| Authors:
Timothy S. Zwier; M. Matti Maricq; C. J. S. M. Simpson; Veronica M. Bierbaum; G. Barney Ellison; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Observation of Zeeman Degeneracy Effects in Collisional Intense Field Resonance Fluorescence |
1980 |
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| Authors:
P. D. Kleiber; K. Burnett; J. Cooper; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
|
| We report observation of the scattered spectrum from a Zeeman degenerate atom at high laser intensities. For a J = 0 to J = 1 transition in the presence of collisions, we observe an asymmetric triplet in the polarization parallel to the incident laser and an asymmetric doublet in the polarization perpendicular to the incident laser. |
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| Emission of Mg-Xe Discharge and the MgXe Excimer Band, |
28 DEC 1979 |
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| Authors:
L. Schumann; D. Wildman; A. Gallagher; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Na 32P-32D Line Broadening by Ne, Ar, and Xe, |
02 OCT 1979 |
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| Authors:
D. W. Wildman; L. W. Schumann; A. C. Gallagher; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Resonance Fluorescence in a Weak Radiation Field with Arbitrary Spectral Distribution |
16 JUL 1979 |
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| Authors:
M. G. Raymer; J. Cooper; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Comparison of Collisional Redistribution and Emission Line Shapes |
29 NOV 1978 |
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| Authors:
M. G. Raymer; J. L. Carlsten; G. Pichler; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| Self-Broadening of the T1 377-6 nm Resonance Line |
19 JUN 1978 |
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| Authors:
Goran Pichler; J. L. Carlsten; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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| THE PHOTODETACHMENT CROSS SECTION, ELECTRON AFFINITY AND STRUCTURE OF THE NEGATIVE HYDROXYL ION, |
01 FEB 1966 |
|
| Authors:
Lewis M. Branscomb; JOINT INST FOR LAB ASTROPHYSICS BOULDER CO
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Reports by Corporate Author
