NONFARADAIC 2-DIMENSIONAL PHASE-TRANSITION ON SMOOTH SURFACES - AN EXAMPLE FOR TIME-DEPENDENT HOMOGENEOUS NUCLEATION

Two dimensional film formation on smooth surfaces has been investigate d theoretically. The commonly used exponential law for nucleation and its limiting cases in connection with the Avrami theorem are examined critically. A new model for describing nucleation on surfaces on the b asis of the classical nucleation theory is proposed. This model takes into account the rime-dependent supersaturation caused by the simultan eous processes of adsorption of molecules from the bulk to the surface and the real phase transition. The model was proofed experimentally b y the investigation of condensation of 5-bromocytosine on mercury elec trodes in aqueous Na2SO4-electrolyte solution. On the basis of the new model the experimental results can be for the first time explained co nsistently.