## 3 Results and Discussion
The single column of H arrangement surrounded by white line in Figure 5a transforms to P arrangement by growth of the three columns in the P domain toward the upper right. The STM-induced transformation from H to P arrangement strongly supports the conclusion that P arrangement is thermodynamically stable. Figure 4: Morphological evolution of a PCDYol film by continuous STM scanning at room temperature (\(I_{\rm set}\) = 10 pA, \(V_{\rm bias}\) = \(-\)800 mV, 3.6 Hz). These images were obtained at the same surface region from the (**a**) first, (**b**) 8 th, and (**c**) 16 th STM scans. The lamellar structure of H arrangement can be seen, and is indicated by a pair of white lines. The H domain indicated by white line in (**a**) shrinks and eventually disappears during the continuous STM scanning. Figure 3: Morphological changes observed after annealing at 50 \({}^{\circ}\)C. (**a**) Typical STM image showing coexistence of H and P arrangements in the PCDYol film prepared by quasi-LB (\(I_{\rm set}\) = 6 pA, \(V_{\rm bias}\) = 800 mV, 3.6 Hz). Domain boundaries are indicated by white lines. The area ratio of P arrangement is 0.4. The stripe intervals of H and P arrangements are suggested by pairs of white lines. (**b,c**) STM images of the film after annealing at 50 \({}^{\circ}\)C for (**b**) 300 s (\(I_{\rm set}\) = 6 pA, \(V_{\rm bias}\) = 800 mV, 3.6 Hz) and (**c**) 3600 s (\(I_{\rm set}\) = 10 pA, \(V_{\rm bias}\) = \(-\)500 mV, 3.6 Hz). Finally, we show that drastic morphological changes of PCDYol monomolecular films occur when the annealing temperature is increased up to 80 \({}^{\circ}\)C. Figure 6a shows the AFM image of the PCDYol monomolecular film formed by spin-coating. Before annealing, the surface was completely covered by only H arrangement domains. After annealing the sample in the range of 40 to 70 \({}^{\circ}\)C, the P domains are observed as shown in Figure 6b. However, Figure 6c shows that the stripe contrasts disappear in the wide range after 80 \({}^{\circ}\)C annealing for 600 s. There are many islands, which are imaged 0.2 nm higher than the surroundings as shown in the inset of the figure. As clearly found in the enlarged image (Figure 6d), the lamellar structure of P arrangement is observed only on the islands, and the extensive region around the islands shows no regular pattern as reported on the liquids of other compounds [12; 13; 14]. Considering the molecular weight, it is difficult to expect that PCDYol molecules evaporate from the surface in an amount detectable by AFM after annealing at 80 \({}^{\circ}\)C for 600 s. Moreover, the height difference between the island and the surroundings is much smaller than the thickness of PCDYol molecule. Therefore, we consider that in the region other than the islands PCDYol molecules remain in glass state. The height difference between the island and surrounding in the AFM image is probably artificial, caused by the deformation of the soft glass region due to the mechanical force during the AFM scanning. In the quenched disordered phase, as already reported for the thin film of C\({}_{32}\)H\({}_{66}\)[15], the chain molecules probably have conformational defects. It is therefore reasonable to speculate that the affinity to the HOPGs surface decreases in the glass region, allowing the PCDYol to move away from the AFM tip. At 80 \({}^{\circ}\)C ordered monomolecular films on HOPG melt into liquid. We infer that the islands of P arrangement nucleated during quenching down to room temperature or formed during the rising of temperature. This melting point of 80 \({}^{\circ}\)C for the ordered monomolecular film on HOPG is about 20 \({}^{\circ}\)C higher than that of the bulk crystal of 59 \({}^{\circ}\)C. Similarly, it has been reported that the melting points of the monomolecular films of \(n\)-alcohols on the graphite surface are higher than those of the bulk solids [16; 17]. Figure 5: Successive STM images showing detailed features of the movement of the P/H interface by STM scanning (\(I_{\text{set}}=10\) pA, \(V_{\text{bias}}=-800\) mV, 3.5 Hz).