Contact Us

Dr Debbie Hammond d.hammond@sheffield.ac.uk

Prof. Graham Leggett
graham.leggett@shef.ac.uk

Chemistry Department
University of Sheffield
Dainton Building
Brook Hill
Sheffield
S3 7HF

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.

RIGHT: SIMS species maps of a partial fingerprint on silicon wafer.

Sample Preparation for XPS: Remember to 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. Please 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 - please contact us for details.

Magnetic samples The Axis Ultra 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 Ultra, but the experimental set up for these samples is slightly different. If you have magnetic samples that you would like to submit for XPS analysis, then please contact us prior to booking the instrument to discuss the available options.

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. Please discuss these latter two options with the experimental officer prior to booking the instrument.

Fibres We have a special sample holder for fibres.

Access to the XPS instrument is charged on a 'per session' basis. A 24 hour period contains two sessions - one day-time session and one overnight session. The instrument is loaded with samples at 8:00am and 4:00pm respectively.

It is not possible to state the number of samples that can be analysed in a single session as this will depend on the number of analysis points per sample, analysis angles, and the number of high resolution spectra required per sample. Below are some guidelines which may help you to plan your experiments and make best use of the time available to you. Please contact the experimental officer for advice regarding the number of sessions you require.

Survey Scans typically take 3 - 4 mins to acquire.

High Resolution Scans take between 5 and 20 mins per analysis point, depending on the abundance of the element in question.

Sample Preparation for SIMS: Remember to 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. Please ask the experimental officer for advice if required.

Typical samples for SIMS are 1 - 1.4 cm2 in size and up to 4 mm thick. Thicker samples may also be accommodated - please contact us for details.

Powders There are a few universally accepted methods of preparing powdered samples for SIMS. 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. Please discuss these latter two options with the experimental officer prior to booking the instrument.  

Access to the SIMS instrument is charged on a 'per session' basis. A 24 hour period contains one 8 hour session. The instrument is loaded with samples at 8:20am.

It is not possible to state the number of samples that can be analysed in a single session as this will depend on the number of analysis points per sample, the number, size and resolution of images and the mode (discussed below). Below are some guidelines which may help you to plan your experiments and make best use of the time available to you. Please contact the experimental officer for advice regarding the number of sessions you require.

Spectra Spectra in either positive or negative mode typically take 3-4 mins to acquire.

High Mass Resolution Imaging Mode In this mode images are obtained from which spectra can be extracted from specified areas. Images take approximately 5 min to acquire.

High Spatial Resolution Imaging Mode High resolution images can be obtained with spatial resolution of ~150 nm, in this mode the mass resolution is compromised. High resolution images can take 20 min - 1 hour for < 500 µm images. For larger images the acquisition time is significantly increased.