Beam-foil light source

As we have seen the beam-foil light source offers many possibilities for studies of spectra, lifetimes and level separations and extensive data have been collected during the last 20 years [6.37-41]. Comprehensive reviews of the field of beam-foil spectroscopy have been written [6.42-48]. 

Finally, the beam-foil light source and its applications will be described. These techniques were introduced in 1963 by Bashkin and Kay [6.26, 6.27]. The principles of beam-foil spectroscopy are illustrated in Fig. 6.3. Ions of the element to be studied are produced with a well-defined energy (velocity) in... 

There are two practical difficulties. One is the measurement of the very small photocurrent, which may be as low as 10" amp, requiring the use of a vibrating reed electrometer or similar instrument. The second is that, for work functions above 5 eV, Vq lies in the far ultraviolet. This makes the study of some adsorptions very difficult and 6 eV is about the practical limit of such measurements. A suitable light source is the quartz mercury arc. The energy of the incident beam can be measured with a calibrated photocell, a vacuum thermopile or a radiometer. A suitable cell for adsorption studies is shown in Fig. 11. The sample being studied forms the cathode B. It can be a metal foil or a film formed by evaporation from the filament E. A wire C is fused through the glass to make contact with the... 

---