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Electron Microscopy and X-ray Microanalysis Facility (EMXMF)

Main instruments:

  • JEOL JXA-8530F Plus field emission electron microprobe
  • FEI MLA650 environmental scanning electron microscope (ESEM)
  • Hitachi SU-70 field emission analytical scanning electron microscope (FESEM)
  • Horiba XGT-7000V x-ray analytical microscope (microXRF)

Other equipment:

  • Olympus BX40F4 digitised light optical microscope
  • BalTec SCD 050 sputter coater (Au, Pt, Cu films)
  • Ladd 40000 and HHV Auto306 carbon evaporators
  • Balzers CPD 030 critical point dryer (CO2 drying)

Electron Probe Microanalysis (EPMA) and Scanning Electron Microscopy (SEM) are closely related techniques for high-magnification imaging and spatially resolved chemical analysis of solid samples. Their focussed electron beam excites various secondary signals: Secondary electrons (SE) show surface morphology, backscattered electrons (BSE) local differences in mean atomic number. Crystal structure and orientation can be determined by electron backscatter diffraction (EBSD). Cathodoluminescence (CL) can be used to assess local variation in defect chemistry. X-rays are detected by wavelength and energy dispersive spectrometers (WDS, EDS) to measure variations in the local chemical composition. Whereas SEM is optimized for high-resolution microscopy, EPMA is mainly used for quantitative chemical analysis of micrometer-sized volumes, for which the samples have to be flat and polished. Non-conductive samples have to be coated (C, Au, Pt). Fresh biological specimens can be observed uncoated using the FEI in low vacuum or environmental mode. The microXRF uses a primary x-ray beam and EDS for lower resolution chemical microanalysis.

Our electron microprobe is predominantly used to determine the chemical composition of minerals in geological rock sections. More specialised applications include monazite U/Th/Pb geochronology to determine the age of rocks, or trace element distribution in sulphide minerals or quartz to gain knowledge about their formation.

Our SEMs are used as imaging and microanalytical tools for a wide range of scientific disciplines.  Typical applications range from determination of elemental distribution (x-ray mapping) or mineral associations and texture in rocks (MLA mode), counting and measuring phytoplankton to investigate the effects of global warming, monitoring the manufacturing of microcapillaries used in separation chemistry to imaging of insects for taxonomy.

For accurate quantitative chemical analysis on any of the instruments, the samples have to be flat and polished.  In general, specimens have to be dry and vacuum stable. For EPMA and SEM, non-conductive samples are coated with carbon, gold or platinum. However, fresh plant specimens can be investigated uncoated in the environmental and low vacuum modes of the FEI instrument.

The Hitachi FESEM provides ultra high resolution particularly at low accelerating voltages, which enables imaging of nanometer-sized surface features of vacuum-stable specimens with very thin or completely without coating. It also has an electron backscatter diffraction (EBSD) system to determine crystal structure and orientation in crystalline materials.

The x-ray analytical microscope or μXRF (micro x-ray fluorescence analyser) employs a high energy x-ray beam to excite secondary x-rays in the sample. The mono-capillary primary optics focus the x-ray beam to a diameter of 10 or 100 micrometers, thus allowing spatially resolved chemical analysis of the elements Na-U. The energy-dispersive x-ray spectrometer (EDS) can be used for qualitative, standardless semi-quantitative analysis, and full quantitative analysis, using calibration curves obtained on standard reference materials. It can operate in spot-mode, where individual sites of interest on a sample are analysed, or in mapping-mode, where 2-dimensional element distribution maps are created. A transmission x-ray detector captures primary x-rays after they passed through the sample to show local differences in density and chemical composition, thus creating an image much like a medical x-ray image. Samples not withstanding vacuum (such as fresh biological material) can optionally be analysed in air with reduced light element sensitivity. No coating or other sample preparation is necessary. However, for quantitative analysis a flat, polished surface is required.

Detailed instrument configuration:

JEOL JXA-8530F Plus field emission electron microprobe

  • installed March 2017
  • Schottky field emission source, beam current up to 2uA, beam diameter 3nm @ 30kV/10pA, 50nm @10kV/100nA
  • 5 wavelength dispersive spectrometers with 140mm Rowland circle and the following analysing crystals and detectors:
    • Sp1: TAP/PETJ/LDE2/LDEB, P10 detector
    • Sp2: LIFL/PETL, Xe detector
    • Sp3: PETL/LDE1L, P10 detector
    • Sp4: TAPL/PETL, P10 detector
    • Sp5: LIFL/PETL, Xe detector
  • computer control by JEOL PC-EPMA and Probe Software Inc. "Probe For EPMA" and "Probe Image" software packages
  • integrated Thermo UltraDry 30mm2 SDD EDS (MnKa resolution 127eV) with Pathfinder Pinnacle software (elements Be-U)
  • JEOL SE, BSE and panchromatic CL imaging detectors
  • JEOL xCLent IV hyperspectral CL system with quartz optics, Ocean Optics grating spectrometer, peak fitting
  • built-in reflected light optical microscope
  • 3-axis motorised stage, XY range 90x100mm, 1um repeatability
  • fully oil-free vacuum system with ion, turbomolecular and scroll pumps
  • IBSS GV10x asher (plasma cleaner) installed on airlock for sample pre-cleaning, fully automatic
  • liquid nitrogen cooled anticontamination cold plate with Norhof auto-refiller for up to 5 days continuous operation


  • installed March 2015
  • tungsten source
  • 3 vacuum modes: high vacuum, low vacuum (large field of view, up to 130 Pa), environmental (up to 1300 Pa)
  • FEI detectors: Everhardt-Thornley SE, CBS solid state BSE, Large Field SE (for low vacuum), Gaseous SE (for ESEM)
  • Gatan PanaCLF panchromatic CL detector with RGB filters
  • Bruker Quantax Esprit 1.9 EDS system with two XFlash 5030 SDD detectors, MnKa 133 eV resolution, combined throughput up to 400kcps
  • 5-axis motorised stage, XYZ range 150x150x65mm
  • Peltier cooling stage
  • Mineral Liberation Analysis (MLA) software package v3.1: Programmed mainly for the mining industry, this software independently controls the instrument for quantitative phase/mineralogical and textural analysis, but can be used for many other purposes such as rare phase search.

Hitachi SU-70 analytical field emission SEM

  • installed February 2011
  • Schottky thermal field emission source
  • ultra-high resolution (1.0 nm @ 15kV, 1.6 nm @ 1kV for SE imaging)
  • high vacuum operation only (i.e. no variable pressure in chamber)
  • Hitachi in-chamber and in-lens scintillation detectors, Super ExB filter, beam deceleration
  • Hitachi in-chamber 5-segment solid state BSE detector, retractable
  • in-column Faraday cup with picoammeter for beam current measurement
  • anticontamination cold plate, liquid nitrogen cooled
  • 5 axis motorised fully eucentric stage, XYZ range 110x110x40mm
  • Oxford AZtec EDS/EBSD system with 
    • X-Max 80 SDD EDS, MnKa 125 eV resolution, elements B-U, large area hyperspectral mapping, standardless and standards-based quantification, feature analysis
    • HKL NordlysNano EBSD camera & forescatter detector system, HKL & Channel 5 software packages, Synergy EDS/EBSD integration, HKL, ICSD & American Mineralogist phase databases
  • Gatan ChromaCL2 colour cathodoluminescence imaging system with integrated BSE detector, Digital Micrograph 3 software, automated mosaic acquisition, simultaneous acquisition of SE, iBSE and colour CL images.

Horiba XGT-7000V microXRF

  • installed April 2008
  • Rh x-ray tube operating at 15, 30, or 50 kV, max. 1 mA
  • X-ray guide tube cartridge for 10 or 100 micrometer beam size (selectable in software)
  • NaI(Tl) scintillator transmission x-ray detector
  • Horiba high-purity Si Be-window EDS, liquid nitrogen cooled, MnKa 148 eV resolution, possible elements Na-U
  • Oxford Inca-based software package and pulse processor
  • Navigation using 3 CCD cameras and 4 light sources from different angles
  • Sample dimensions max. 300x300x80 mm, 1 kg
  • Stage travel range 100x100x20 mm
  • Can be operated under vacuum (rotary vane pump) or at room atmosphere

Digitised Olympus BX40F4 light microscope

  • reflected and transmitted light, simple analyser for transmitted and reflected light, polariser currently only for transmitted light
  • 50x to 500x magnification, MPlan metallographic objectives, binocular eyepiece
  • Olympus U-RLA brightfield/darkfield vertical illuminator and U-AC condensor
  • Lang MCL-2/Scan100x100 digital stage, motorised (x, y axes)
  • Pixera PVC100C USB CCD camera
  • computer control via Microbeam Services Digimax software
  • main purpose: pre-select points for analysis on the SEM and EPMA to save time on these instruments. Digimax coordinate files can be imported and recoordinated on both the SEM and the EPMA.

Two workstations for off-line data processing, with the following software packages on at least 1 PC

  • Probe Software Probe for EPMA and Probe Image
  • FEI MLA v2.9 and v3.1
  • Oxford AZtec, INCA, HKL, Channel 5 software
  • Bruker Quantax 400 v1.9.5
  • Thermo Pathfinder v1.3
  • Gatan Digital Micrograph 3 (for colour CL image processing)
  • JEOL xCLent IV spectral cathodoluminescence software
  • Cameca PeakSight v4.2
  • ImageJ-Fiji
  • Virtual WDS (U Cambridge, UK)
  • Micronex MinIdent-Win 4
  • Golden Software Grapher and Surfer
  • Casino Monte Carlo simulation (U Sherbrooke, CA)

For more information, contact:

Dr Karsten Goemann (Senior Research Fellow & scientist in charge)
Dr Sandrin Feig (Laboratory Analyst)

Past instrumentation:

  • Jeol JXA-50A electron microprobe (1974-1989)
  • Cameca SX-50 electron microprobe (#242, 1989-2003)
  • Cameca SX-100 electron microprobe (#846, 2003-2019)
  • Philips 505 SEM (1982-2006)
  • Electroscan 2020 ESEM (1994-2005)
  • FEI Quanta 600 MkI ESEM (2005-2015)