![siloxane xps peak siloxane xps peak](https://pubs.rsc.org/image/article/2021/RA/d0ra10565a/d0ra10565a-f2_hi-res.gif)
‘That makes life very difficult for XPS.’ Dirty solution ‘Your peaks are moving constantly on the screen as you are measuring,’ explains spectroscopist Grzegorz Gre c zynski of Linköping University in Sweden. For non-conductive samples, however, this is ineffective. This is easily avoided in a conductive sample by connecting the surface to earth, so that it regains the lost electrons and remains neutral. The problem is that when electrons are liberated from a surface it can accumulate positive charge and therefore holds its remaining electrons more tightly. Grzegorz Greczynski, Linköping University no method is better than the wrong method Kai S i egbahn shared the 1981 physics Nobel prize for developing the technique. These constitute a spectral fingerprint for the material. XPS works by bombarding a surface with x-rays and using the energies of the emitted electrons to infer the binding energies of the material’s electrons. The difference is the potential energy needed to extract the electron, or the binding energy. When a photon does liberate an electron, the electron comes out with less energy than the incident photon. This established that light comprised quanta – now called photons. XPS is based on the photoelectric effect: the Nobel prize-winning discovery made by Albert Einstein in 1905 explaining why frequency, not intensity, determines whether or not light can liberate electrons from a material. However, the standard technique used to calibrate XPS on semiconducting or insulating surfaces is worse than useless, say two spectrocopists, and as a result countless suspect results have entered the literature. X-ray photoelectron spectroscopy (XPS) is one of the most widely-used techniques to detect and identify molecules on surfaces, and its use has grown dramatically in recent years. Questions are now being raised over the trustworthiness of results obtained on certain materials