EDP Sciences
Free Access
Volume 413, Number 2, January II 2004
Page(s) 395 - 401
Section Cosmology
DOI https://doi.org/10.1051/0004-6361:20031574
Published online 18 December 2003

A&A 413, 395-401 (2004)
DOI: 10.1051/0004-6361:20031574

Forsterite amorphisation by ion irradiation: Monitoring by infrared spectroscopy

J. R. Brucato1, G. Strazzulla2, G. Baratta2 and L. Colangeli1

1  INAF Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
    e-mail: colangeli@na.astro.it
2  INAF Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
    e-mail: gianni@ct.astro.it, gbaratta@ct.astro.it

(Received 20 May 2003 / Accepted 15 September 2003)

We present experimental results on the crystal-amorphous transition of forsterite (Mg 2SiO 4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been synthesised in the laboratory and irradiated with low energy (30-60 keV) ion beams. Structural changes during irradiation with H +, He +, C +, and Ar ++ have been observed and monitored by infrared spectroscopy. The fraction of crystalline forsterite converted into the amorphous form is a function of the energy deposited by nuclear collision by ions in the target.

Laboratory results indicate that ion irradiation is a mechanism potentially active in space for the amorphisation of silicates. Physical properties obtained in this work can be used to model the evolution of silicate grains during their life cycle from evolved stars, through different interstellar environments and up to being incorporated in Solar System objects.

Key words: methods: laboratory -- techniques: spectroscopic -- ISM: dust, evolution -- ISM: cosmic rays

Offprint request: J. R. Brucato, brucato@na.astro.it

SIMBAD Objects in preparation

© ESO 2004

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