Skip to content
6CCVD Research

Visible‐IR and Raman microspectroscopic investigation of three Itokawa particles collected by Hayabusa - Mineralogy and degree of space weathering based on nondestructive analyses

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2015-08-24
JournalMeteoritics and Planetary Science
AuthorsL. Bonal, R. Brunetto, Pierre Beck, E. Dartois, Z. Dionnet
InstitutionsUniversité Paris-Sud, Institut d’Astrophysique Spatiale
Citations33
AnalysisFull AI Review Included

6CCVD Technical Analysis & Application Brief: Diamond Substrates for Extraterrestrial Spectroscopy

Section titled “6CCVD Technical Analysis & Application Brief: Diamond Substrates for Extraterrestrial Spectroscopy”

Executive Summary

Section titled “Executive Summary”

This study details the nondestructive analysis of three Hayabusa-returned Itokawa asteroid particles using Raman and Visible-Near-Infrared (VIS-NIR) microspectroscopy. The core findings and material requirements are summarized below:

  • Diamond Substrate Criticality: Synthetic Type II diamond windows (2 mm diameter) were used as spectrally transparent, low-signature substrates, enabling high-precision analysis of the rare, micrometer-scale asteroidal particles.
  • Mineralogical Confirmation: Raman spectroscopy confirmed the particles are Mg-rich olivine (F076±5) and pyroxenes (Ca-rich En50Wo50, Ca-poor En85), characteristic of LL4/L/LL chondrites.
  • Space Weathering Analysis: VIS-NIR reflectance spectra revealed differential space weathering intensity among the grains, confirming the presence of nanophase metallic iron (npFeº) and iron sulfides (FeS) resulting from solar wind irradiation.
  • Micro-scale Analysis Demand: Experimental techniques required exceptionally high spatial resolution (1-2 µm laser spots) and low power densities (< 500 W mm-2) to prevent sample alteration, necessitating high-optical-quality diamond components.
  • Timescale Constraint: Modeling suggests particle RA-QD02-0174 experienced space weathering for approximately 8 x 105 yr, approximately four times longer than the other particles, providing critical constraints on asteroidal surface evolution.
  • 6CCVD Application: Replicating or extending this crucial planetary science research requires high-purity, optical-grade Single Crystal Diamond (SCD) windows, a core capability of 6CCVD.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Substrate Material UsedSynthetic Type II Diamond-Optical windows for IR/Raman analysis (2 mm diameter)
Raman Excitation Wavelength 1532nmSOLEIL Synchrotron Beamline
Raman Excitation Wavelength 2514nmLabRam (Ar+ laser)
Raman Laser Spot Size (Min)~1µmRequired for spatial resolution of individual minerals
Raman Power Density (Max)500W mm-2Nondamaging limit for raw particles
Reflectance Range Analyzed0.4-1.0µmVIS-NIR spectral range (includes 1 µm band)
Reflectance Geometryi = 45°, e = 0°°Bidirectional setup
Dominant Olivine CompositionF076±5-Forsterite content (consistent with LL4 chondrites)
Nanophase Fe Volume Fraction (Modeled)0.11%Estimated in highly weathered particle RA-QD02-0174
Estimated Max Space Weathering Duration8 x 105yrCalculated for RA-QD02-0174 using Hapke model

Key Methodologies

Section titled “Key Methodologies”

The study relied on the use of high-purity diamond substrates and highly sensitive microspectroscopy techniques to ensure nondestructive analysis of the precious extraterrestrial samples.

  1. Sample Preparation and Housing:

    • Particles were housed either in original JAXA containers or transferred manually under Earth’s atmosphere (in a clean room) onto modified compression cells.
    • The cells utilized synthetic Type II diamond windows (2 mm diameter) specifically chosen for their spectral transparency across the VIS-NIR and Raman ranges.
    • A gasket was inserted between the two diamond windows to prevent mechanical crushing of the delicate ~30-54 µm regolith grains.

  2. Raman Microspectroscopy (Mineral Identification):

    • Performed in both punctual and automatic mapping modes (1 µm grid pattern).
    • High spatial resolution (~1.0-2.0 µm spot size) was maintained using objectives up to x50.
    • Low laser power (< 0.3 mW or < 500 W mm-2) was strictly controlled to avoid laser-induced alteration or damage to the sample mineralogy.

  3. Visible-NIR Reflectance Microspectroscopy (Space Weathering Analysis):

    • Performed using a specialized grating spectrometer coupled via infrared transparent fibers to an optical microscope.
    • Utilized fixed bidirectional geometry (incidence i = 45°, collection e = 0°).
    • Reference spectra were collected using a high-quality 99% Spectralon standard.

  4. Data Interpretation:

    • Mineral chemical composition was estimated using established Raman calibrations (e.g., Kuebler et al. 2006).
    • Space weathering effects (spectral reddening) were quantified using spectral slope calculations and modeled using the Hapke (2001) theory, which employs Maxwell-Garnett effective medium theory to estimate nanophase iron inclusion abundance.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

This demanding research, requiring ultralow background and high optical purity in the substrate material, highlights the essential role of high-grade CVD diamond windows. 6CCVD is uniquely positioned to supply the materials required to replicate or advance this type of planetary science research.

Paper Requirement6CCVD Material SolutionTechnical Specification Alignment
Spectrally Transparent SubstrateOptical Grade Single Crystal Diamond (SCD)Provides the exceptional purity and near-zero spectral signature required for sensitive VIS-NIR (0.4-1.0 µm) and Raman (514/532 nm) analysis. SCD ensures maximum signal-to-noise ratio.
Micrometer Scale AnalysisCustom Thin-Film SCD/PCDCapabilities for SCD thickness down to 0.1 µm, minimizing material absorption and interference effects crucial for micro-analysis of tiny particles (< 55 µm).
Custom DimensionsPrecision CVD Diamond WafersThe paper used 2 mm diameter windows. 6CCVD provides custom diamond plate dimensions up to 125 mm (PCD) or precision laser cutting services to match any required cell geometry.
High-Precision Surface FinishUltra-Smooth Polishing (Ra < 1 nm SCD)Minimized surface roughness prevents light scatter (Ra < 1 nm for SCD and < 5 nm for inch-size PCD), which is vital for reproducible bidirectional reflectance measurements.
Future Integrated SensingCustom Metalization CapabilitiesWhile this paper was non-destructive, extending this research (e.g., integrating electrical contacts for subsequent testing) is supported by 6CCVD’s in-house metalization (Au, Pt, Ti, W, etc.) services.

Engineering Support & Application Extension

Section titled “Engineering Support & Application Extension”

6CCVD’s commitment to advancing scientific endeavors in extreme environments makes us the ideal partner for cosmochemistry and planetary science researchers.

  • Material Selection Expertise: 6CCVD’s in-house PhD engineering team specializes in diamond material selection and optimization for high-sensitivity spectroscopy, including applications for Visible-NIR and Raman microspectroscopy of challenging extraterrestrial samples.
  • Replication and Scale-Up: We provide consistent, high-volume supply of custom optical windows needed for international research consortia requiring spectrally stable components for complex multi-analytical protocols.
  • Global Logistics: We provide reliable global shipping (DDU default, DDP available) to ensure sensitive components reach international research facilities (like those referenced in the paper, e.g., SOLEIL, JAXA partners) efficiently and securely.

For custom specifications or material consultation on asteroidal mineralogical or similar high-purity spectroscopic projects, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Abstract Hayabusa‐returned samples offer a unique perspective for understanding the link between asteroids and cosmomaterials available in the laboratory, and provide insights on the early stages of surface space weathering. This study characterizes the mineralogy and the extent of space weathering of the three Itokawa particles RA ‐ QD 02‐0163, RA ‐ QD 02‐0174, and RA ‐ QD 02‐0213 provided by JAXA to our consortium. We report here a series of results based on nondestructive analyses through visible‐near‐infrared reflectance and Raman spectroscopy. Results were obtained on the raw particles, both in their original containers and deposited on diamond windows. Identification of the minerals, characterization of their elemental compositions, and measurements of their relative abundances were led through Raman spectroscopy in punctual and automatic mode. Reflectance spectra in the visible and near‐ IR wavelengths constrain the mineralogy of the grains and allow direct comparison with the surface of Itokawa. The spectra reflect the extent of space weathering experienced by the three particles. Particle RA ‐ QD 02‐0163 consists of a heterogeneous mixture of minerals: olivine (Fo 76 ) dominates an assemblage with both Ca‐rich (En 50 , Wo 50 ) and Ca‐poor (En 85 ) pyroxenes. The elemental compositions of the silicates are consistent with those previously reported for distinct Hayabusa particles. Particles RA ‐ QD ‐0174 and RA ‐ QD 02‐0213 are solely composed of olivine, whose chemical composition is similar to that observed in RA ‐ QD 02‐0163. It has been previously shown that the S‐type asteroid 25143 Itokawa is a breccia of poorly equilibrated LL 4 and highly equilibrated LL 5 and LL 6 materials. The three particles studied here can be related to the least metamorphosed lithology ( LL 4) based on the high forsterite content of the olivine. Neither carbonaceous matter nor hydrated minerals were detected through Raman on the three allocated particles. The NIR ‐ VIS reflectance (incidence = 45°, light collection at e = 0°) spectra of the three particles, in particular the 1 μm band, are consistent with the presence of both olivine and pyroxene detected via Raman. The spectra of particles RA ‐ QD 02‐0163 and RA ‐ QD 02‐0213 are also fully compatible with the ground‐based observations of asteroid (25143) Itokawa in terms of both spectral features and slope. By contrast, particle RA ‐ QD 02‐0174 has a similar 1 μm band depth but higher (redder) spectral slope than the surface of Itokawa. This probably reveals a variable extent of space weathering among the regolith particles. RA ‐ QD 02‐0174 may contain a higher amount of nanophase metallic iron and nanophase FeS. Such phases are products by space weathering induced by solar wind, previously detected on other Itokawa particles.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 1983 - Rarity of lunar soil analogs in meteorites
  2. 1998 - Chondritic meteorites

Reads Similar to This

EPR study of Si‐ and Ge‐related defects in HPHT diamonds synthesized from Mg‐based solvent‐catalysts Review of Electrical Resistivity Measurements and Calculations of Fe and Fe-Alloys Relating to Planetary Cores Electrochemical oxidation of the increasingly used disinfectant benzalkonium chloride