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Title: Molecular dynamics simulation of amorphization in forsterite by cosmic rays

Abstract

We have examined cosmic ray interactions with silicate dust grains by simulating a thermal spike in a 1.25 million atom forsterite (Mg2SiO4) crystal with periodic boundaries. Spikes were generated by giving a kinetic energy of 1 or 2 eV to every atom within a cylinder of radius 1.73 nm along the [001] direction. An amorphous track of radius ~3 nm was produced for the 2 eV/atom case, but practically no amorphization was produced for 1 eV/atom because of effective dynamic annealing. Chemical segregation was not observed in the track. These results agree with recent experimental studies of ion irradiation effects in silicates, and indicate that cosmic rays can cause the amorphization of interstellar dust.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
901163
Report Number(s):
PNNL-SA-55042
3564; 8208; KC0201020; TRN: US200720%%356
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1):172-176; Journal Volume: 255; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMORPHOUS STATE; ANNEALING; ATOMS; COSMIC RADIATION; DUSTS; INTERSTELLAR GRAINS; IRRADIATION; KINETIC ENERGY; MAGNESIUM SILICATES; MOLECULAR DYNAMICS METHOD; SEGREGATION; SILICATES; SIMULATION; THERMAL SPIKES; cosmic ray interactions; interstellar dust; amorphization; silicate; forsterite; molecular dynamics simulation; Environmental Molecular Sciences Laboratory

Citation Formats

Devanathan, Ram, Durham, Philip, Du, Jincheng, Corrales, Louis R., and Bringa, Eduardo M. Molecular dynamics simulation of amorphization in forsterite by cosmic rays. United States: N. p., 2007. Web. doi:10.1016/j.nimb.2006.11.021.
Devanathan, Ram, Durham, Philip, Du, Jincheng, Corrales, Louis R., & Bringa, Eduardo M. Molecular dynamics simulation of amorphization in forsterite by cosmic rays. United States. doi:10.1016/j.nimb.2006.11.021.
Devanathan, Ram, Durham, Philip, Du, Jincheng, Corrales, Louis R., and Bringa, Eduardo M. Fri . "Molecular dynamics simulation of amorphization in forsterite by cosmic rays". United States. doi:10.1016/j.nimb.2006.11.021.
@article{osti_901163,
title = {Molecular dynamics simulation of amorphization in forsterite by cosmic rays},
author = {Devanathan, Ram and Durham, Philip and Du, Jincheng and Corrales, Louis R. and Bringa, Eduardo M.},
abstractNote = {We have examined cosmic ray interactions with silicate dust grains by simulating a thermal spike in a 1.25 million atom forsterite (Mg2SiO4) crystal with periodic boundaries. Spikes were generated by giving a kinetic energy of 1 or 2 eV to every atom within a cylinder of radius 1.73 nm along the [001] direction. An amorphous track of radius ~3 nm was produced for the 2 eV/atom case, but practically no amorphization was produced for 1 eV/atom because of effective dynamic annealing. Chemical segregation was not observed in the track. These results agree with recent experimental studies of ion irradiation effects in silicates, and indicate that cosmic rays can cause the amorphization of interstellar dust.},
doi = {10.1016/j.nimb.2006.11.021},
journal = {Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1):172-176},
number = 1,
volume = 255,
place = {United States},
year = {Fri Feb 16 00:00:00 EST 2007},
month = {Fri Feb 16 00:00:00 EST 2007}
}