Mid-infrared reflectance spectroscopy of synthetic glass analogs for mercury surface studies

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • Andreas Morlok
  • Christian Renggli
  • Bernard Charlier
  • Maximilian P. Reitze
  • Stephan Klemme
  • Olivier Namur
  • Martin Sohn
  • Dayl Martin
  • Iris Weber
  • Aleksandra N. Stojic
  • Harald Hiesinger
  • Peter Tollan
  • Cristian Carli
  • Karin E. Bauch
  • Joern Helbert

Abstract

We have synthesized and analyzed by mid-infrared reflectance spectroscopy silicate glasses that are representative for the glasses on the surface of Mercury. The glass compositions are based on high-pressure laboratory experiments and the resulting compositions of the glass phase. The spectra are of interest for investigating the surface of Mercury using the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument on board of the ESA/JAXA BepiColombo mission.

Both powdered fractions and polished blocks have been analyzed. Powdered size fractions of 0–25 μm, 25-63 μm, 63-125 μm, and 125–250 μm were measured in reflectance in the thermal infrared (2–20 μm). Spectra for powdered bulk glasses (1.6 wt% - 19.0 wt% MgO) show a single, dominating Reststrahlenband (RB, 9.3–9.8 μm), a Christiansen Feature (CF; 7.6 μm - 8.1 μm), and a size dependent Transparency Feature (TF; 11.6–11.9 μm). Micro-FTIR analyses of polished blocks of glasses (3.4–26.5 wt% MgO) have characteristic bands at 7.8–8.2 μm (CF), and 9.3–9.9 μm (RB). Only few olivine crystalline features were observed.

Spectral features correlate with compositional characteristics, e.g. SiO2 content or SCFM (SiO2/(SiO2 + CaO + FeO + MgO) index. The strongest correlation between band features CF and the strong RB are with Mg/Si. No simple mixture of glass spectra from this study is able to reproduce the entire ground based spectrum of the surface of Mercury. However, Mg-rich glasses reproduce identified features at 8.5 μm, 9.9 μm and 12.4 μm.

Bibliographical metadata

Original languageEnglish
Pages (from-to)114363
JournalIcarus
Volume361
Early online date6 Feb 2021
DOIs
Publication statusPublished - 6 Feb 2021

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