Cathodoluminescence imaging and spectral analyses of phosphates in the Martian meteorites: A review. A. Gucsik 1, W. J. Protheroe, Jr. 2, J.A.R. Stirling 3, K. Ninagawa 4, H. Nishido 5, T. Okumura 5, N. Matsuda 6, Sz. Berczi 7, Sz. Nagy 7, A. Kereszturi 7 and H. Hargitai 7 1 Max Planck Institute for Chemistry, Mainz, Germany 2 AOL Inc., Houston, USA 3 Geological Survey of Canada, Ottawa, Canada 4 Okayama Unversity of Science, Dept. of Applied Physics, Okayama, Japan 5 Okayama Unversity of Science, RINS, Okayama, Japan 6 Okayama Unversity of Science, ISEI, Tottori, Japan 7 Eotvos 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

Mechanism of CL (unshocked)-Band Gap Model Processes of CL produced in insulator crystals based on Goetze, 1999

CONDUCTION BAND (E c ) VALANCE BAND (E v ) BANDGAP(Eg)BANDGAP(Eg) ENERGY(E)ENERGY(E) Near UV λ ≤ 200 nm Near IR λ ≥ 900 nm Activator Trap 3 4 „Extrinsic“ „Intrinsic“ External energy source (irradiation) Photon emission Energy transfers Energy migrations No photon emission Absence of or closely- spaced electron traps Mechanism of CL (shocked)-Band Gap Model based on Nasdala, 2003 Kayama et al. (2007) Okumura et al. (2007)

CL micrograph and spectrum of apatite Reference material based on Goetze, 1999

Samples and Experimental Procedure: We studied two polished thin sections of the Y 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 nA at room temperature. CL spectra were recorded in the wavelength range of nm, with 1 nm resolution by the photon counting method using a photomultiplier detector, Hamamatsu Photonics R2228.

Y nakhlite SE SEM-CL 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 CO 2 and OH. Matsuda et al. (2007)

Research Team CAN-AM Mars Meteorite 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)

Equipment CAN-AM Mars Meteorite Research Team Equipment used in the research of the Mars meteorites is based at the Geological Survey of Canada, 601 Booth St., 7 th floor, Ottawa, Ontario, Canada. The equipment shown below is manufactured by Cameca. EOS – Electron Optic Service, Inc., Nepean, ONT., Canada Cameca, MBX and Camebax are trademarks of Cameca (France) Kevex is a trademark of Kevex Corporation. 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 Cathodo- luminescence (CL) spectrometry and imaging system by EOS.

Equipment CAN-AM Mars Meteorite Research Team Also used in the analysis of the Mars meteorites at the Geological Survey of Canada is the Cameca SX-50. Advance Microbeam - Advance Microbeam Corporation Cameca, MBX and Camebax are trademarks of Cameca (France) PGT is a trademark of Princeton Gamma Tech Corporation. 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.

ALH 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 atmospheric- rock-fliud interactions on Mars.

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