AbstractThe condensation of tungsten vapours onto tungsten field emitter tips is studied. It is shown that at temperatures, at which the desorption flux can be neglected, the nuclei appear at a definite adatom concentration. Its value is found to be about 1013atoms/cm2, which corresponds to 1% from the monolayer. This value confirms our previous theoretical considerations, i. e. nucleation from a dilute adlayer takes place only if the desorption energy is lower than the vaporisation heat of the condensate. With condensation on its own surface this condition is always satisfied.