Cathodoluminescence imaging and spectral analyses of
phosphates in the Martian meteorites: A review.
A. Gucsik1, W. J. Protheroe, Jr. 2, J.A.R. Stirling3, K. Ninagawa4, H. Nishido5, T.
Okumura5, N. Matsuda6, Sz. Berczi7, Sz. Nagy7, A. Kereszturi7 and H. Hargitai7
1Max
Planck Institute for Chemistry, Mainz, Germany (gucsik@mpch-mainz.mpg.de)
2AOL
Inc., Houston, USA
3Geological
Survey of Canada, Ottawa, Canada
4Okayama
Unversity of Science, Dept. of Applied Physics, Okayama, Japan
5Okayama
Unversity of Science, RINS, Okayama, Japan
6Okayama
Unversity of Science, ISEI, Tottori, Japan
7Eotvos
Lorand University, Budapest, Hungary
NIPR, Tokyo, 07 June 2007
Contents
Basics of the cathodoluminescence
signal.
CL properties of some Martian meteorites.
Conclusions.
•Purpose
•Scanning Electron Microscopy-Cathodoluminescence (SEM-CL)
techniques provide better spatial resolution images of the minerals
than the standard optical microscope ones.
• Moreover, SEM-CL spectral information might give some details on
the activator elements presented in the in minerals.
•These observations can aid to understand more about the formation
mechanism of different types of phosphates.
•It is important to note, that CL characteristics of the Martian
meteorite samples have not been documented in great details, so far.
•Non-destructive method.
based on Goetze, 1999
based on Goetze, 1999
based on Goetze, 1999
based on Goetze, 1999
based on Goetze, 1999
based on Goetze, 1999
based on Goetze, 1999
Mechanism of CL (unshocked)-Band Gap Model
Processes of CL produced in insulator crystals
based on Goetze, 1999
Mechanism of CL (shocked)-Band Gap Model
CONDUCTION BAND (Ec)
„Intrinsic“
1
2
„Extrinsic“
3
1
2
3
4
Near UV
λ ≤ 200 nm
Trap
E
N
E
R
G
Y
(E
)
B
A
N
D
G
A
P
(E
g)
Activator
Near IR
λ ≥ 900 nm
VALANCE BAND (Ev)
External energy
source (irradiation)
No photon emission
Photon emission
Energy transfers
Absence of or closelyspaced electron traps
Energy migrations
Kayama et al. (2007)
Okumura et al. (2007)
based on Nasdala, 2003
Reference material
CL micrograph and spectrum of apatite
based on Goetze, 1999
Samples and Experimental Procedure: We
studied two polished thin sections of the
Y000593
nakhlite
Martian
meteorite
supplied from the National Institute of
Polar Research (NIPR, Tokyo, Japan).
SEM-CL imaging and CL spectral analyses
were performed on the selected thin
sections coated with a 20-nm thin film of
carbon in order to avoid charge build-up.
SEM-CL images were collected using a
scanning electron microscope (SEM),
JEOL 5410LV, equipped with a CL detector,
Oxford Mono CL2, which comprises an
integral
1200
grooves/mm
grating
monochromator attached to reflecting light
guide with a retractable paraboloidal
mirror. The operating conditions for all
SEM-CL investigation as well as SEM and
backscattered electron (BSE) microscopy
were accelerating voltage: 15 kV, and 3.05.0 nA at room temperature. CL spectra
were recorded in the wavelength range of
300-800 nm, with 1 nm resolution by the
photon
counting
method
using
a
photomultiplier
detector,
Hamamatsu
Photonics R2228.
Y-000593 nakhlite
SE
SEM-CL
Apatite (Ap) was found as a mesostasis
mineral, which occurs in veinlets between
mostly clinopyroxene (Cpx) and plagioclase
(Pl).
EDS analysis reveals that this apatite is a
chloroapatite, which contains minor fluorine,
but uncertain of CO2 and OH.
CL
Matsuda et al. (2007)
CAN-AM
Mars Meteorite
Research Team
Research Team
Members of the research team are John A. R. Stirling (GSC),
Walter J. Protheroe Jr., and Pat A. Hunt (GSC).
GSC – Geological Survey of Canada (Natural Resources Canada)
From left:
John A. R. Stirling,
Walter J. Protheroe Jr.
and Pat A. Hunt
Research Team
Photograph by: Katherine E. Venance (GSC)
CAN-AM
Mars Meteorite
Research Team
Equipment
Equipment used in the research of the Mars meteorites is based
at the Geological Survey of Canada, 601 Booth St., 7th floor,
Ottawa, Ontario, Canada. The equipment shown below is
manufactured by Cameca.
Cameca MBX – Camebax Electron
Microprobe
This instrument is a fully automated
electron microprobe with four
wavelength spectrometers and a
Kevex – Electron Dispersive
Spectrometer (EDS). Upgrades to this
system have included digital imaging,
advanced EDS imaging, and Cathodoluminescence (CL) spectrometry and
imaging system by EOS.
EOS – Electron Optic Service, Inc., Nepean, ONT., Canada
Cameca, MBX and Camebax are trademarks of Cameca (France)
Kevex is a trademark of Kevex Corporation.
CAN-AM
Mars Meteorite
Research Team
Equipment
Also used in the analysis of the Mars meteorites at the Geological
Survey of Canada is the Cameca SX-50.
Cameca SX-50 – Camebax Electron
Microprobe
The SX-50 is a new generation of
automated electron microprobes. This
one has four spectrometers, a
digital imaging system and a EDS
System by PGT. The software has been
upgraded by Advance Microbeam.
Advance Microbeam - Advance Microbeam Corporation
Cameca, MBX and Camebax are trademarks of Cameca (France)
PGT is a trademark of Princeton Gamma Tech Corporation.
ALH-84001 sample N fragments (#3734, #3738, and #3739)
SE
SEM-CL
Colour-enhanced CL
Whitlockite (Beta-Ca-phosphate)
Conclusions
CL spectroscopy combined with SEM-CL
imaging is a powerful technique to
characterize phosphates in the Martian
meteorites.
This also can aid to distinguish anhydrous
or hydrous phosphates.
This technique also can play a key role in
the
in-situ
measurements
of
the
mineralogical evidences of the atmosphericrock-fliud interactions on Mars.
Thank you very much for your attention