Physics and Engineering of Radiation Detection

688 Chapter 12. Radiation Spectroscopy

Eγ Eγ Eγ

Photoelectron Energy

Photoelelectron Intensity

1s

2s

2p

−Eb,1s −Eb,2s −Eb,2p

Figure 12.1.14: A simple XPS photoelectron spectrum.

Each peak corresponds to emission of photoelectrons from

an atomic level. A typical spectrum contains a number of

peaks corresponding to different elements in the sample.

Sample

Vacuum

Pump

DetectorElectron Output

Trajectory

Electron

Focusing

Lenses

Hemispherical

Deflection Assembly

X−ray Source

Enclosure

Vacuumed

Figure 12.1.15: Conceptual design of an electron energy ana-

lyzer.

of a series of focusing lenses. These lenses perform two tasks. The first one is to
focus the electrons to the center of the slit to minimize their loss. The other task is
to slow down the electrons such that they fall within the required energy passband
of the analyzer. This slowing down is however not arbitrary since then the energy
information will be lost. The second main component of an HDA consists of two
metallic hemispheres. Application of electric potentials on these hemispheres creates