| abstract |
The present invention provides an electron spectroscopy apparatus 2 comprising a high energy particle source 12 for irradiating a sample 6, an electron detector system 16 for detecting electrons emitted from the sample, and an ion gun 8 for delivering a polycyclic aromatic hydrocarbon (PAH) ion beam 10 to the sample 6, wherein the ion gun 8 comprises a PAH ion source. The polycyclic aromatic hydrocarbon may comprise anthracene, pyrene, ovalene, or, more preferably, coronene or dicoronylene. In an embodiment, the PAH is located in a heated chamber (22 in Figure 2) and vaporised to produce gas phase PAH. The gas phase PAH molecules are then ionised by electron impact, extracted from the ion source via an extraction field and focussed using ion optics. The PAH ion beam 10 is preferably used for removing material from outer layers of the sample 6 when performing depth analyses, and provides improvements in terms of reduced sample damage and deposition of unwanted material. |