Figure 1. Heterogeneous nucleation of liquid II on various solid surfaces at 220 K.

(a) Time evolution of LLT in the presence of a TPP crystal, which was observed with polarizing microscopy under the crossed Nicols condition. At the beginning (0 min), we observe only the TPP crystalline spherulite with the Maltese cross pattern. Thereafter, the layer of liquid II, which has no birefringence, is formed on the surface of the TPP spherulite (40 min) and its thickness linearly grows with time (60, 80 min) (see f). (b) Time evolution of LLT in the presence of a PET surface. In this case, LLT proceeds while forming a thin film of liquid II, which also grows linearly with time (see f): compete wetting. White dashed lines indicate the location of the surface. (c, d) Time evolution of LLT in the presence of PTFE (c) and gold (d) surface. Nuclei of liquid II are preferentially formed on the substrates with a finite contact angle (θ≤90°): partial wetting. (e) Time evolution of LLT in the presence of an aluminium surface. Nuclei of liquid II do not have any contact to the aluminium surface and normal NG-type droplet growth in bulk was observed: non-wetting. The scale bars correspond to 10 μm. (f) Growth kinetics of a complete wetting layer of liquid II. Time evolution of the thickness of the wetting layer (left axis) formed on a TPP crystal (a), PET (b) and PVDF (Fig. 2b) surface, together with the radius of a droplet of liquid II (right axis). Time t is shifted by birth time t₀. Temperature was 220 K. All data can be well fitted by linear functions, indicating the same growth rate irrespective of the substrate materials. The growth rate of the wetting layer is estimated as 2.95±0.15 nm s⁻¹.