SAES GETTERS

The atomically clean, well-ordered Ni(lOO) surface was obtained by using a standard cleaning procedure as described in detail elsewhere [17]. The deposition of potassium was achieved by evaporation from a SAES getter source [18]. Reagent grade (99.999% purity) gases of O2, H2 and CH4 were introduced into the UHV chambers through leak-valves. 

Sodium or rubidium atoms were deposited in much the same way as Al- and Ca-atoms, with the exception that the atoms were obtained from SAES getter sources (zeolites), which could be mounted, one at a time, into a heated glass shield (to maintain a stream of atoms in the correct direction in the UHV chamber), then opened in UHV and maintained clean during the course of the measurements1. Spectroscopically clean metal films could be prepared from these sources, as a check on source purity. 

In the present work, Ca, CsF, Al, Ag and ytterbium (Yb) were evaporated in the evaporation chamber using either tungsten baskets or tantalum cells. The amount of evaporants was monitored by a quartz crystal microbalance. It was calculated from the changes of the oscillation frequency of the crystal and in turn governed by the bulk densities of the evaporants where the densities of the Ca, CsF, Al, Ag and Yb are 1.55, 1.88, 2.70, 10.49 and 6.57 g/cm3, respectively [89]. For alkali metal deposition, a SAES getter source of Cs was installed in the evaporation chamber, where the source has been degassed thoroughly before deposition. 

Figure 4.3 A stainless steel outgassing bench eqnipped with a quadrupole mass spectrometer and an external oven for vacuum bake-out (Reproduced by courtesy of SAES Getters SpA, Italy).

Figure 4.22 Picture of the SAES Getters SpiroTorr SRG connected to a vacuum panel.

Still, a better assessment is necessary through longer term tests and, possibly, through accelerated tests able to provide experimental data within a shorter time. Activity is ongoing in SAES Getters Laboratories, as well as in various other research centres to provide such an assessment. 

Results obtained in SAES Getters Laboratories for 50 x 50 x 2 cm panels aged for several months at 60 °C are shown in Figure 4.28. 

The author would like to thank Dr. Paolo della Porta, President and CEO of SAES Getters SpA, for his continuous support and long lasting commitment to VIP technology. The author also acknowledges Dr. Bruno Ferrario, Corporate R D Director, for fruitful... 

P. Manini, inventor Saes Getters SpA, assignee WO 9803850A1, 1998. 

W. Lamb and R. Zeiler, Presented at the Vacuum Insulation Panel Symposium, Baltimore, MD, 1999. Paper available from the SAES Getters web site, http // www.saesgetters.com. 

---