Paper SS-ThP26
Characterisation of Self-Assembled Monolayers Using Angle Resolved XPS

Thursday, October 18, 2007, 5:30 pm, Room 4C

Self assembled monolayers (SAMS) are increasingly important as a means to functionalise surfaces and to control surface properties or reactivity. The length of many of the molecules used in these layers and, therefore, the thickness of the monolayers formed by them is often less than the attenuation length of the photoelectrons emitted in the XPS process. This means that the XPS technique is ideal for characterising the layers. The additional benefits coming from ARXPS are also important for the determination of layer orientation and thickness. For this work, the ARXPS data was collected in parallel over a 60 degree range, without the need to tilt the samples. This means that it is possible to collect angle-resolved XPS maps of the surface to examine the uniformity of the layers. If the layers are uniform, data can be collected as a map over a large area to minimise the X-ray flux density used in the analysis. By examining a number of samples having the same SAM at the surface, the precision of the measurements can be determined. Obviously, high precision is required if the two-dimensional uniformity is to be investigated. It will also be shown, using a range of SAM’s, that the techniques developed for extracting non-destructive depth profiles from ARXPS data can be successfully applied to these materials. Results will be reported from SAMs formed from alkane thiols and from molecules containing additional functional groups.