Search Results - (Author, Cooperation:J. M. Ajello)

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  1. 1
    Staff View
    Publication Date:
    2011-04-23
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  2. 2
    P. C. Frisch ; M. Bzowski ; G. Livadiotis ; D. J. McComas ; E. Moebius ; H. R. Mueller ; W. R. Pryor ; N. A. Schwadron ; J. M. Sokol ; J. V. Vallerga ; J. M. Ajello
    American Association for the Advancement of Science (AAAS)
    Published 2013
    Staff View
    Publication Date:
    2013-09-07
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  3. 3
    Pang, K. D. ; Ajello, J. M. ; Franklin, B. ; Shemansky, D. E.

    College Park, Md. : American Institute of Physics (AIP)
    Published 1987
    Staff View
    ISSN:
    1089-7690
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Chemistry and Pharmacology
    Notes:
    We have measured the electron impact emission cross sections for CH4 and C2H2 at 200 eV in a crossed beam laboratory system. Included in the study are all vacuum ultraviolet (VUV) emission features from 40 to 200 nm. The features are entirely from the atomic dissociation fragments (C i, C ii, and H). The Lyman series of H is observed to truncate near principal quantum number n=10 due to the long lifetime and to the high kinetic energy of the excited H fragments. The threshold region of the excitation functions has been measured at an energy resolution of 0.2–1.0 eV for the Lyman-α and Lyman-β transitions of H and C i (165.7, 193.1 nm) multiplets; and several distinct appearance potentials (AP) have been detected. For example, appearance potentials of Lyman-α from dissociation of CH4 and C2H2 are noted at several energies, including the first observations of a Lyman-α AP from C2H2 at 16.3 eV.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  4. 4
    Ajello, J. M. ; Franklin, B.

    College Park, Md. : American Institute of Physics (AIP)
    Published 1985
    Staff View
    ISSN:
    1089-7690
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Chemistry and Pharmacology
    Notes:
    We have measured in the laboratory the electron impact emission cross sections for O2 at 200 eV. Included in the study are all emission features in the extreme ultraviolet from 40 to 131 nm at a resolution of 0.5 nm. The features are entirely from the dissociation products (OI, OII, OIII). Additionally we have measured the excitation functions from 0 to 400 eV for characteristic OI multiplets at 98.9 and 102.6 nm and for OII multiplets at 53.9 and 83.3 nm. We find the OI multiplets are formed near the dissociation limit whereas the OII multiplets have a threshold about 10 eV above the dissociation limit. We also determine the total VUV emission cross section of O2 from 40 to 200 nm and indicate the effects of autoionization to the measured emission spectrum.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  5. 5
    QUESSETTE, J. A. ; MILLIER, F. ; AJELLO, J. M.

    [s.l.] : Nature Publishing Group
    Published 1972
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The rocket .was spinning, thus allowing observations in all azimuthal directions within ±15 from the horizontal plane. The signals given by the two detectors are consistent throughout the flight. The results presented here are those provided by the photomultiplier. Our preliminary analysis ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  6. 6
    Staff View
    ISSN:
    1572-9672
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract The Voyager Ultraviolet Spectrometer (UVS) is an objective grating spectrometer covering the wavelength range of 500–1700 Å with 10 Å resolution. Its primary goal is the determination of the composition and structure of the atmospheres of Jupiter, Saturn, Uranus and several of their satellites. The capability for two very different observational modes have been combined in a single instrument. Observations in the airglow mode measure radiation from the atmosphere due to resonant scattering of the solar flux or energetic particle bombardment, and the occultation mode provides measurements of the atmospheric extinction of solar or stellar radiation as the spacecraft enters the shadow zone behind the target. In addition to the primary goal of the solar system atmospheric measurements, the UVS is expected to make valuable contributions to stellar astronomy at wavelengths below 1000 Å.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  7. 7
    Staff View
    ISSN:
    1572-9672
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113–432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg × 0.1 deg for illuminated disc observations and 1 deg × 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg × 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170–432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses