Types of Samples:
The samples that can be analyzed by XPS are all solids ranging from films, powders to frozen liquids including inorganic compounds, metal alloys, semiconductors, polymers, elements, catalysts, glasses, ceramics, paints, papers, inks, woods, plant parts, makeup, teeth, bones, medical implants, bio-materials, viscous oils, glues, ion-modified materials and many others.
General Sample Handling:
Good sample preparation methods are vital in surface science as the signals emanating from surface contamination can overwhelm the signals from the sample.
- Gloves (powder free nitrile or polyethylene) 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 petri dishes and well plates (polystyrene), or clean glass vials. Avoid ALL other plastic containers, including plastic sample bags. A good alternative to plastic or glass containers is new, clean aluminum foil (NOT commercial Reynolds Wrap).
- In situ sample cleaning by Ar+ etching is available for the removal of thin oxide layers but will cause surface chemical damage and reduce available analysis time. The C60 cluster gun preserves surface chemistry and composition especially for organic and polymer surfaces but significantly reduces analysis time.
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If the samples have been immersed in electrolytes/salt solutions then wash in distilled water and dry in air. Samples with high surface area, high vapor pressure or which have been immersed in liquids will require longer to pump down prior to insertion into the instrument. In general, samples should be inserted into the load lock the previous evening.
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Samples which are sensitive to oxygen or water vapor should be mounted and loaded into the vacuum transfer vessel in the glove box.
XPS Sample Preparation:
Typical samples for XPS are 5 mm to 10 mm square and up to 4 mm thick. Thicker samples may also be accommodated - please contact us for details.
Powders
There are several general methods to prepare powdered samples and users should AVOID to use preparation materials that contain similar elements as the sample:
- Press the powder into clean, high purity indium foil.
- Dissolve the powder in a suitable solvent and then drop cast onto the surface of a clean silicon wafer.
- Sprinkle the powder onto the surface of sticky carbon conductive tape or pressed into a tablet for analysis.
Fibers
We have a special sample holder for fibers.
Magnetic samples
Magnetic samples can be analyzed in the VersaProbe, but the experimental set up for these samples is slightly different. Please contact us prior to booking the instrument to discuss the available options.