How do low-pressure conditions help keep prepared surfaces clean?

In vacuum technology, low-pressure conditions are essential for maintaining the cleanliness of prepared surfaces because they significantly reduce the number of molecular impacts per second.1

At normal atmospheric pressure, a vast number of molecules move at high speeds, frequently colliding with surfaces and causing contamination. By lowering the pressure, the density of these molecules decreases, which directly reduces the frequency of these impacts. This is particularly critical in clean-surface studies, where researchers must minimize the rate at which residual gases form a monolayer of contaminants on a freshly prepared surface.1