Sample preparation
Good sample preparation methods are vital in surface science as the signals emanating from surface contamination can overwhelm the signals from the sample.
Gloves and clean tweezers must be used and any glassware must be thoroughly cleaned before use. Tweezers should be cleaned regularly by sonication in isopropyl alcohol (IPA).
Samples can be stored or transported in clean poly(styrene) petri dishes and well plates, or clean glass vials. Avoid all other plastic containers, including plastic sample bags. A good alternative to plastic or glass containers is new, clean aluminium foil.
An argon etch is available to XPS users for in situ sample cleaning. This method is recommended for the removal of thin oxide layers however it will reduce your available analysis time so it should be avoided where possible.
SIMS species maps of a partial fingerprint on silicon wafer.
Sample preparation for XPS
Ensure that the analysis side of your sample is obvious. If required, add a note in the sample handling procedures section of the COSHH form. Ask the experimental officer for advice if required.
Typical samples for XPS are 0.5 - 1 cm2 in size and up to 4 mm thick. Thicker samples may also be accommodated, contact us for details.
Magnetic samples
The Axis Supra uses a magnetic immersion lens to focus the photoelectrons emitted from the surface towards the detector. Magnetic samples can still be analysed in the Axis Supra, but the experimental set up for these samples is a little different leading to a slightly reduced signal intensity.
Powders
There are a few universally accepted methods of preparing powdered samples for XPS. Of these, the favoured method is to press the powder into clean, high purity indium foil.
Alternatively, the powder may be dissolved in a suitable solvent and then drop cast onto the surface of a clean silicon wafer.
Finally, powders that can not be prepared by either of the above methods can be either sprinkled onto the surface of sticky carbon tape or pressed into a tablet for analysis.
Purchasing surface analysis
Surface analysis can be purchased on a per sample, or half-day / full day basis. We can provide the as-collected data for you to analyse yourself, and we can also provide training to University of Sheffield members on how to do this. The University of Sheffield has a site licence for Casa XPS, the data analysis software we use. Alternatively, we can analyse the data for you and provide a brief report.