Space weathering simulations through controlled growth of iron nanoparticles on olivine

    Authors

    T. Kohout; J. Cuda; J. Filip; D. Britt; T. Bradley; J. Tucek; R. Skala; G. Kletetschka; J. Kaslik; O. Malina; K. Siskova;R. Zboril

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    Abbreviated Journal Title

    Icarus

    Keywords

    Asteroids, surfaces; Moon, surface; Regoliths; Spectroscopy; SPECTRAL REFLECTIVITY; OPTICAL-PROPERTIES; ASTEROID SURFACES; LUNAR; REGOLITH; NEAR-EARTH; LASER; PARTICLES; ORIGIN; BELT; FE; Astronomy & Astrophysics

    Abstract

    Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe(0)) during space weathering plays major role in these spectral changes. A laboratory procedure for the controlled production of npFe(0) in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe(0) in the 7-20 nm size range. A logarithmic trend is observed between amount of npFe(0) and darkening, reduction of 1 gm olivine absorption band, reddening, and 1 gm band width. Olivine with a population of physically larger npFe(0) particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as the larger, similar to 40-50 nm sized, npFe(0) particles do not contribute to the spectral slope change as efficiently as the smaller npFe(0) fraction. A linear trend is observed between the amount of npFe(0) and 1 mu m band center position, most likely caused by Fe2+ disassociation from olivine structure into npFe(0) particles. (C) 2014 Elsevier Inc. All rights reserved.

    Journal Title

    Icarus

    Volume

    237

    Publication Date

    1-1-2014

    Document Type

    Article

    Language

    English

    First Page

    75

    Last Page

    83

    WOS Identifier

    WOS:000337556400008

    ISSN

    0019-1035

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