Nucleation and cavity formation

Single atomic layers nucleated and propagating over crystal surface creating concentration gradient and tending towards cavity formation.  Timelapse movie of average subtracted RICM images at 0.1 s interval.  The dark areas correspond to a smaller distance to the confining glass and thus to the newly formed single molecular layer 0.33 nm thick. Same crystal as in Movie S1 and Fig. S4 with supersaturation 0.055. Due to higher nucleation rate than in Movie S1 the diffusion of ions does not replenish ion concentration at the centre resulting in a concentration gradient from edge to centre. Due to the concentration gradient nucleation centres are located at the crystal edge and the molecular layer step flow is slower towards the centre than along the edges. Fluctuations in nucleation frequency causes fluctuations in concentration gradient and stability of cavity.