Over the years we have developed highly accurate and reliable methods of following the sticking and thermal desorption of weakly bound atoms and molecules on well-defined sngle crystal surfaces. Desorption rates and coverages can be followed over up to 5 orders of magnitude, and desorption parameters as well as sticking coefficients as functions of coverage extracted. The development of cryogenic techniques in combination with these methods have made it possible to investigate all rare gases and molecular hydrogen on several close-packed metal surfaces (Pt(111), Ru(001), Ru(001) covered with H, D, K, or Cs layers); very recently we have extended this to helium (sub)monolayers. Some examples from the following range will be given:

 
-         The understanding of sticking of heavy and light species on the bare surfaces

-         The dependence of sticking on coverage

-         The distinction between wetting and nonwetting layers in desorption

-         The importance of lateral interactions, observed e.g. by observation of 2D phase transitions, finite size effects, and decompression of layers in desorption and sticking

-         The observation of collisional desorption 

-         The direct observation of translational cooling in desorption

-         The recent extension to helium monolayers, and the observation of photoinduced desorption caused by room temperature blackbody radiation.