EPMA technical information

Edinburgh’s EPMA Facility is built around a JEOL JXA iHP200F instrument installed in May 2026. This instrument produces high accuracy, high precision, fully quantitative analyses of almost any combination of elements between boron and uranium, with exceptional capability between oxygen and uranium.

The technique of EPMA uses an incident electron beam focused to diameters of 1 micron or less on the sample surface, to generate X-rays that identify the elements and their concentrations within samples. Routine detection limits are typically 60 – 600 ppm, depending on the element and host material.

We can provide high-quality analysis of an extensive range of materials including:

• minerals
• metals and alloys
• glasses
• ceramics
• bone
• tooth

The Edinburgh EPMA Facility is exceptionally versatile, with strong capabilities in fields such as:

• earth and environmental sciences
• materials sciences
• metallurgy
• biological and medical sciences
• archaeology
• forensics
• manufacturing, process and quality control

In addition to quantitative analysis of specific locations on samples, the iHP200F can produce qualitative and quantitative element distribution maps with resolutions as high as 1 micron, chemical line profiles and analyses of thin layers.

The iHP200F is designed for automation and when samples permit can be set up for automated analyses overnight and during weekends, maximising data collection and cost-effectiveness.

Electron probe microanalysis

Our JEOL JXA iHP200F instrument is equipped with five wavelength dispersive spectrometers and JEOL energy dispersive detector. It has a Field Emission electron source that can provide very high analytical resolution and high beam currents.

Sample observation is simple via back-scattered and secondary electron imagery and in plane- and cross-polarised reflected and transmitted light with an optical microscope at a magnification of x400.

Analytical target locations can be identified offline prior to analysis on a geo-logging microscope or clients may navigate their samples via their own georeferenced sample images.

Many specialised data collection, and online and offline processing functionalities are available via JEOL’s software and an additional comprehensive suite by Probe Software which expands the capabilities of the iHP200F. These include quantitative X-ray mapping and chemical profile scans, phase mapping, very low concentration trace element analysis, fully integrated ED and WD quantitative analysis, quantitative analysis of thin layers and analysis of non-flat samples.

Diffracting crystals of six types enable analysis of elements between boron and uranium. The configuration of these within the five WD spectrometers permits analysis of almost any element combination, making the iHP200F an exceptionally versatile instrument.

The large analysing crystals (TAPL, PETL and LIFL) in spectrometers 2-4 enable higher analytical precisions, lower detection limits and faster analysis times. They allow trace element analysis down to tens or hundreds of ppm, and high-quality analysis of beam-sensitive minerals such as glasses, carbonates and phyllosilicates.

Tephra analysis

The specifications of the iHP200F are ideal for analysis of glassy materials such as tephras. 

Its large TAPL and PETL analysing crystals enable measurement of Na and K before mobilization during analysis, even using electron beam diameters of 5 mm and 3 mm.

The iHP200F’s exceptional electron and optical imaging capabilities allow location of very small crypto tephra grains, identification and avoidance of crystals within glasses, The energy dispersive detector allows rapid discrimination between glass and mineral fragments.

Secondary electron image of an approximately 10 x 15 micron crypto-tephra grain, after analysis. The beam diameter was 5 microns.	Image
Backscattered electron image of plagioclase and magnetite crystals within a melt inclusion within a clinopyroxene of the Fimmvörduhals fissure eruption, Iceland, 2010.	Image

Please discuss any queries related to sample preparation or format with us well in advance of your scheduled booking.

Contact details and access to the facility

Electron Probe

To enable fully quantitative analysis, samples must be prepared in specific ways:

• Samples must be vacuum compatible and stable under electron bombardment.
  • The operating vacuum is approximately 10 -5 Pa.
• Samples must be flat, well-polished and as free from surface voids as possible.
  • Final polishing should use 0.25 mm diamond abrasive or 0.03 mm alumina.
  • Samples with porosity should be vacuum-impregnated with resin to fill void space. 
  • Samples must be cleaned after polishing to remove abrasive particles and lubricants. This can be done at the EPMA Facility if necessary.
• Samples must be cohesive, so as not to shed particles whilst in the iHP200F.
• Samples must be in a format compatible with the JEOL sample holders, which accommodate most standard formats. Permitted formats are:
  • Thin sections: 45-48mm long, up to 25mm wide, 1mm thick with up to 0.5mm thick polished sample above the glass slide
  • Disks: 25.5mm or 29.5mm diameter, thickness 5-25mm
  • It may be possible to accommodate other formats - please discuss details with us. Please use epoxy resin for sample preparation. Lakeside, Canada Balsam and styrene-based resins must not be used.
• Insulating samples need to be coated before analysis with a thin film of carbon. This is performed at the EPMA Facility. Please ensure that samples arrive two working days before your EPMA booking to enable coating.

Tephra Analysis

Tephra samples require special preparation methods to allow high quality analysis.

Samples with grain sizes down to around 125 mm can be prepared as 25.5 mm diameter resin disks or as thin sections. The method for preparing resin disks is described by:

• Lowe D.J. 2011. Tephrochronology and its application: A review. Quaternary Geochronology, 6, 107-153.

The finest grained tephras are prepared as 25.5 mm diameter resin disks according to the methods described by:

• Blockley S.P.E, , Pyne-O’Donnell S.D.F., Lowe J.J., Matthews I.P., Stone A., Pollard A.M., Turney C.S.M. and Molyneux E.G. 2005. A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments. Quaternary Science Reviews, 24, 1952–1960.
• Kuehn S.C. and Froese D.G. 2010. Tephra from Ice—A Simple Method to Routinely Mount, Polish, and Quantitatively Analyze Sparse Fine Particles. Microscopy and Microanalysis, 16, 218-225.
• Hall M. and Hayward C.L. (2015). Preparation of micro- and crypto-taphras for quantitative microbeam analysis. In: Austin, W. E. N., Abbott, P. M., Davies, S. M., Pearce, N. J. G. & Wastegaard, S. (eds.) Marine Tephras. Geological Society Special Publication, 398. The Geological Society, London.
• Iverson N.A., Kalteyer D., Dunbar N.W., Kurbatov A. and Yates M. 2017. Advancements and Best Practices for Analysis and Correlation of Tephra and Cryptotephra in Ice. Quaternary Geochronology, 40, 45-55.

If you have any questions concerning preparation methods for your tephras, please contact us.