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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 198440.0, MPI für Astronomie / Publikationen_mpia
Structural processing of enstatite by ion bombardment
Authors:Jäger, C.; Fabian, D.; Schrempel, F.; Dorschner, J.; Henning, Th.; Wesch, W.
Date of Publication (YYYY-MM-DD):2003
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:Astronomy and Astrophysics
Volume:401
Start Page:57
End Page:65
Review Status:not specified
Audience:Not Specified
Abstract / Description:During their lifetime, cosmic dust silicates
suffer from a continuous processing by annealing,
cosmic ray and UV irradiation, destruction and
possibly also interstellar recondensation. Since
the discovery that a significant proportion of
stardust silicates leaves their star in
crystalline form, the question arose as to why
the interstellar silicate dust component does not
show any indication of crystallinity.
Amorphization due to ion irradiation is one
possible explanation for the effect. In this
paper, the results of irradiation experiments of
submicrometre-sized clinoenstatite
(MgSiO3) particles with 400 keV
Ar+ and 50 keV He+ ions are
presented. The irradiation doses have been varied
between 1x1016 and 1x1018 ions/cm2 for He+ ions and
1x1014 up to 5x1014 ions/cm2 for Ar+ ions.
These doses are comparable to those values that
an interstellar silicate grain should be exposed
to during its average life-time of
4x108 years. Threshold values for
amorphization have been amounted to
1x1017 and 3x1014 ions/cm2 for 50 keV He+ and
400 keV Ar+ ions. Besides the
structural changes in the microcrystallites
morphological modifications in the grains, but no
change of the chemical composition are found.
Conclusions of potential astrophysical relevance
have been drawn.
Free Keywords:ISM: cosmic rays; ISM: dust; extinction; ISM: general
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:Astrophysikalisches Institut and
Universitäts-Sternwarte (AIU), Schillergäßchen
2-3, 07745 Jena, Germany),
AB(Friedrich-Schiller-Universität Jena,
Astrophysikalisches Institut and
Universitäts-Sternwarte (AIU), Schillergäßchen
2-3, 07745 Jena, Germany),
AC(Friedrich-Schiller-Universität Jena, Institut
für Festkörperphysik, Max-Wien-Platz 1, 07743
Jena, Germany), AD(Friedrich-Schiller-Universität
Jena, Astrophysikalisches Institut and
Universitäts-Sternwarte (AIU), Schillergäßchen
2-3, 07745 Jena, Germany),
AE(Friedrich-Schiller-Universität Jena,
Astrophysikalisches Institut and
Universitäts-Sternwarte (AIU), Schillergäßchen
2-3, 07745 Jena, Germany),
AF(Friedrich-Schiller-Universität Jena, Institut
für Festkörperphysik, Max-Wien-Platz 1, 07743
Jena, Germany)
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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