How does the time needed to form a monolayer relate to surface contamination in a vacuum?

In vacuum technology, the time required to form a monolayer is a critical parameter used to determine the maximum permissible pressure for a process. This metric directly relates to surface contamination: by reducing the number of molecular impacts per second through the creation of a vacuum, the rate at which gas molecules strike and adhere to a prepared surface is significantly lowered.1

Essentially, the longer the time needed to form a monolayer, the lower the rate of surface contamination. In clean-surface studies, maintaining a high-quality vacuum is essential because it extends the duration before a surface becomes covered by a layer of residual gas molecules, thereby preserving the integrity of the prepared surface for a longer period.1