infrared spectroscopy of minerals from primitive meteorites: an ir snapshot of an early solar...
TRANSCRIPT
Infrared Spectroscopy of Minerals from Primitive Meteorites: An IR Snapshot of
an Early Solar System.
A. Morlok1,4, M. Koehler2,4, O.N. Menzies3,4, M. M. Grady1,4
1 The Natural History Museum, London2 Institut fuer Planetologie, Muenster
3 Imperial College, London 4 IARC
© European Southern Observatory
Astronomical Infrared Spectra
Formation of a Solar System
© Bill Hartmann
Primitive Meteorites: Components
Calcium-Aluminum Rich Inclusions Chondrules and Matrix
Mainly Silicates, e.g.:Olivine (Mg,Fe)2SiO4
Pyroxene (Mg,Fe)SiO3
‘Glass’
Highly refractory phases, e.g.:Corundum Al2O3
Hibonite CaAl12O19
Melilite Ca2MgSi2O7
Ca2Al2SiO7
What ?
?
(Mid-)infrared spectra from sub-micron dust clouds, young solar systems, circumstellar discs etc. obtained with earth and space based telescopes
Mid-infrared analysis of sub-micron powder of mineral separates and components, from primitive meteorites for comparison with these astronomical spectra
Aim: Comparison of laboratory infrared data of minerals and components with astronomical spectra
© European Southern Observatory
Challenges-Sample Preparation:
-’Pure’ grains/material needed But primitive meteorites are very fine grained, most mineral grains <<100m
-Characterization: What are we actually measuring ?-Preparation of tiny grains for identification, measurement of chemical composition, estimation of homogeneity
-Infrared Measurements-Small amounts of material (~ng) Difficult to prepare/handle Danger of artefacts
-Generally: Efficiency of process – each individual grain counts !
Sample Preparation
Cleaning with Isopropanol and Deionised Water
Picking
Embedding
PolishingCharacterisation
Separation
Grinding FT-IR Analysis (at last)
Separation
Sample
How: FT-IR Techniques (Microscope)-Perkin Elmer AutoImage FT-IR microscope system for mid-infrared: 4000cm-1 to 650cm-1 (2.5m to ~16m), spectral resolution 4cm-1
Transmission/Absorbance
Source
Sample
Detector
+High Quality+Common
-Thin Samples Needed
Reflectance
Source
Sample
Detector
+Easy&Fast
-(Less Common)
ATR
Source
Sample
Detector
+High Quality
-Artefacts-Resolution
Results: Enstatites from Primitive Meteorites I
TW Hya
-Pictoris
Enstatite (En99) From Primitive Meteorite
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
60 65 70 75 80 85 90 95 100
Enstatite Mol%
Ban
d P
ositi
on in
Mic
ron
Results: Enstatites from Primitive Meteorites
Compact, Melilite/Spinel-rich Inclusion (Vigarano CV3.3)
Wark-Lovering Rim:Diopside, Forsterite, Spinel
Interior:Melilite, Spinel
Material Separated ‘In Situ’ from Polished Thick Section
A
8 9 10 12 13m11
TW Hya
-Pictoris
Conclusions & Outlook
-Analyses over a wider range of wavelengths needed (far IR !)-Systematic analysis of all types of components like CAI and chondrules-Effects of environment (temperature…) and size
andso…
-Mid-infrared spectra of components and minerals from primitivechondrites can be easily measured with a variety of techniques-Preliminary comparison with astronomical spectra shows potential -But much more work has to be done ….