For some materials, plasmon loss peaks may occur.
These involve an enhanced probability for loss of a specific amount of energy
due to the interaction between the photoelectron and other electrons. For
conductive metals, the energy loss (plasmon) to the conduction electrons occurs
in well-defined quanta arising from group oscillations of the conduction
electrons[1]. Plasmons attributed to the bulk of the material and
its surface can sometimes be separately identified[2]. An example of plasmon loss peaks in
a spectrum of aluminum metal is presented in Figure 1. In some cases, such as
with Al, the plasmon loss structure can interfere with the assignment and
quantification of other spectral peaks such as Si 2p, Si 2s and P 2p.
Figure 1. Plasmon
loss structure in a spectrum of aluminum metal.
Table 1. Plasmon loss structure peak positions, FWHM and percent peak area (% concentration) from a survey spectrum (160 eV pass energy) of sputter cleaned aluminum metal (Figure 1.)
Reference:
[1] J.F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben, Handbook of X-ray Photoelectron Spectroscopy, Perkin-Elmer Corp, Eden Prairie, MN, 1992.
