X-ray photoelectron spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA), is a technique for analysing the surface chemistry of a material. XPS can measure the elemental composition, chemical state and electronic state of the elements within a material. It is a surface analysis technique with a sampling depth of approximately 1-10 nm. The technique enables identification and quantification of all surface elements (except hydrogen). XPS analysis can be utilised to characterize the layer structure of thin films with sputter depth profiling where elements are quantified as a function of depth. Virtually all vacuum-compatible solid materials including fibres and powder and any species deposited onto a solid surface can be analysed by XPS. Minimal sample preparation is required. The preferred sample dimensions for our XPS instrument are length/width < 10mm and height of 1mm (maximum height 5mm).
Time-of-Flight secondary ion mass spectrometry (TOF-SIMS) is a very sensitive surface analytical technique (< 2nm). The instrument uses a pulsed beam of primary ions focused onto a sample surface, producing secondary ions in a sputtering process. Analyzing these secondary ions provides information about the molecular and elemental species present on the surface. SIMS is a very surface sensitive technique because the emitted particles originate from the uppermost one or two monolayers. TOF-SIMS is a technique where all the elements in the periodic table, including hydrogen, are detected. TOF-SIMS analysis can provide mass spectral information, image information across a sample, and also depth profile information into a sample.
Sample cleanliness is critical for this technique. The surface to be analysed should not be touched by your fingers (even when gloved) or any tools. Plastic bags or boxes should not be used for sample storage or transport since the plastic is likely to have a coating of polydimethylsiloxane (PDMS) which can significantly contaminate the sample surface. Clean glass tubes or fluoroware (Teflon) sample containers are strongly recommended. The largest sample dimensions are 32 x 16 x 7.5 mm (l x w x h). Samples larger than this will need to be cut to size.