Sorption is the process in which one substance takes up and holds another by either absorption or adsorption.

A cryopump is a vacuum pump that traps gases and vapours by condensing them on a cold surface. They are only effective on some gases, depending on the freezing and boiling points of the gas relative to the cryopump's temperature.

The only difference between the two processes that I have observed is the methods in which they trap the gases. Also, sorption is a process while cryopump is a machine.

An example of a material that uses sorption or has a high adsorption rate is zeolite.

Specimens are placed in a vacuum (high vacuum, requiring a cryopump to get to 10^-7 torr. Then the specimen is bombarded with an electron beam (like getting a shock). Not likely that something could survive that.

Achieving high vacuum is difficult because all of the materials exposed to the vacuum must be carefully evaluated for their outgassing and vapor pressure properties.Ultra high vacuum generally requires custom built equipment, strict operational procedures, and a fair amount of trial and error . Ultra high vacuum systems are usually made of stainless steel with metal gasketed conflat flanges. The system is usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials in the system and boil them off. If necessary, this outgassing of the system can also be performed at room temperature, but this takes much more time. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures to minimize residual outgassing during actual operation. Some systems are cooled well below room temperature byliquid nitrogen to shut down residual outgassing and simultaneously cryopump the system.