ULTRAHIGH VACUUM: A SURVEY
ILLINOIS UNIV AT URBANA COORDINATED SCIENCE LAB
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Methods for producing low pressures have now caught up with out means of measuring them, and pressures down to 10 to the -10 Torr are standard in a broad technological sense. Total pressures as low as 10 to the -12 Torr at room temperature have been achieved in a few laboratory experiments. Two new classes of ionization instruments have recently been developed which have ultimate sensitivity below 10 to the -11 Torr, one class for the measurement of total pressures with ultimate sensitivities in the 10 to the -12 to 10 to the -15 Torr range and a second class which involves mass analyzers capable of measuring partial constituents as low as 10 to the -16 Torr. However, in the range of pressures below 10 to the -11 Torr and sometimes considerably higher the surface effects, that is, the chemical and physical interactions which take place at the electrode surfaces of the instruments, begin to be compare to or to dominate the volume effects which they are intended to measure. Since the study of these physical and chemical phenomena can only be carried out by using the best ultra-high vacuum techniques we can devise, there is a mmerging of the scientific and technological motivations to study and understand these processes. These include 1 the kinetics of gas surface interactions at the interface, 2 the interaction of atomic particles, electrons and photons with surfaces, and 3 the nature of the electronic bonds between adsorbed molecules and surfaces.
- Test Facilities, Equipment and Methods