Surface science experiments require a chemically clean sample surface with the absence of any unwanted adsorbates.   There are many techniques and tools to prepare a sample for analysis under UHV conditions.

Aqueous Cleaners / Degreasers

Aqueous cleaners are mostly a combination of various substances like alkaline builders, surfactants, sequestering agents, etc.   Their use is on the rise as their results have proven to be in many cases as good as or better than hydrocarbon cleaners.   Additionally, the wastes generated are less hazardous resulting in less costly disposal.   In the group of hydrocarbon based solvents, there are some newly developed agents like fatty acid esters made of natural fats and oils, modified alcohols and dibasic esters.

Plasma Cleaners

Plasma cleaners utilise low pressure, low temperature oxygen plasmas to provide an ultra-fine cleaning of surfaces that may be contaminated with low levels of organic species.   The UV light in the plasma helps to break H-C bonds whilst the oxygen radicals readily combine with H and C groups, removing them to the gas phase where they are pumped away.   Plasma cleaning also has the effect of rendering many surfaces more hydrophilic making them easier to bond to.

Solvent Cleaners / Degreasers

Solvent degreasing is a process used to prepare a part for further operations such as electroplating or painting.   Typically it uses petroleum, chlorine, or alcohol based solvents to dissolve the machining fluids and other contaminants that might be on the part.

Ultrasonic Baths

An ultrasonic cleaner is a cleaning device that uses ultrasound (usually from 20–400 kHz) and an appropriate cleaning solvent (sometimes ordinary tap water) to clean vacuum components.   The ultrasound can be used with only water but use of a solvent appropriate for the item to be cleaned enhances the effect.