Salient Features of XPS and a Few Practical Examples

XPS is known for its weakly (usually non-) destructive nature and for its universal applicability to solid samples - be they metals, ceramics, or polymers. However, the samples must be solid and vacuum compatible. The most serious limitation is the ex-situ nature of the technique. The instrument is very costly and complex and the monochromatic X-ray sources have low flux. 

The XPS technique is not usually spatially sensitive, sampling depth varies with electron kinetic energy (and material) and the spectra is complicated by secondary features like X-ray satellites. The surface charging in insulators shifts binding energy scale. Hydrogen and helium can not be detected with good sensitivity. 

Using the energies of core levels of various states (Fig. 5.15) and using energy of MgR radiation equal to 1253.6 eV, it is easy to find that the Na Is, 2s and 2p photoelectron peaks resulting from photoionization of the Is, 2s 

The XPS spectrum obtained from a Pd metal sample using MgK radiation is shown in Fig. 5.16. 

From the spectrum given in Fig. 5.16, it is clear that the peaks occur at kinetic energies of about 330, 690, 720, 910, and 920 eV. These energies 

---