Method and device for characterising condensable impurities on a surface

摘要

A method is described for the detection of particulate impurities or impurities incorporated in the surface. The method is based on the role of the impurities as condensation nuclei for a supersaturation of a vaporisable substance, said supersaturation being generated by adiabatic expansion. A spectrum which is dependent on the size of the impurities can be recorded by program-controlled pressure build-up and, consequently, variably producible supersaturations. The nucleation centres which have grown to drop size can therefore be counted, for example, optically. Only certain particles capable of interaction with the substance are activated as condensation nuclei for a given supersaturation by selecting the physico-chemical properties of the condensable substance.