The sorption pump is an oil-free #prevacuum pump that is based on the adsorption of gases on cold surfaces. The colder the surface, the more efficient the pumping is! Therefore liquid nitrogen with a temperature less than 77 degrees Kelvin is used for cooling the adsorber. The adsorber is a porous zeolite with a very large surface area as the pores have a diameter in the range of a few nanometers (or less). If the pump is full, then it needs to be renewed by degassing, which is basically heating the adsorber so that the gas can remove the pump through the outlet.
Vacuum can be understood as space from where matter (for example air) has been removed. It naturally exists in outer space but for certain applications, like materials characterization techniques, it needs to be achieved artificially. The desired level of vacuum is obtained with the help of a suitable vacuum pump. For example low vacuum (low quality vacuum with higher pressure) can be generated with a diffusion pump, scroll compressor pump, rotary vane pump, diaphragm pump or a sorption pump. High vacuum (high quality vacuum with very low pressures) however, can be obtained with high vacuum pumps such as the turbomolecular pump, ion pump, titanium sublimation pump and cryopump. The level of vacuum is measured with devices called vacuum gauges (vacuum meters) like the thermocouple gauge, pirani gauge, penning ionization gauge and the quadrupole mass spectrometer (analyzer). The working principle of vacuum pumps and vacuum gauges is explained with 3D animations in the video lecture above.