A surface-tension-gradient-induced growth phenomenon is reported in lipid monolayer films. The sur-face tension gradient is introduced to the monolayer film by local, subtle heating using the microscope light. This surface tension gradient is responsible for compressing the illuminated area continuously and induces the growth of domains of liquid condensed phase. The evolution of morphology from fractal to faceted and then to dendritic patterns is investigated by in situ observations. The mechanism of pattern formation in this system is discussed.

In this paper we report the spontaneous formation of a nanostructured film by electrodeposition from an ultrathin electrolyte layer of CuSO4. The film consists of straight periodic ditches and ridges, which corresponds to the alternating deposition of nanocrystallites of copper and copper plus cuprous oxide, respectively. The periodicity on the film may vary from 100nm to a few hundred nanometers depending on the experimental conditions. In the formation of the periodically nanostructured film, oscillating voltage/current has been observed across the electrodes, and the frequency depends on the pH of the electrolyte and the applied current/voltage. A model based on the coupling of [Cu2+] and [H+] in the electrodeposition is proposed to describe the oscillatory phenomena in our system. The calculated results are in agreement with the experimental observations.

In our previous work we demonstrated an unusual crystallite aggregate in which the crystallites correlate in crystallographic orientation and form a fractal pattern with strong anisotropy (Wang, M.; et al. Phys. Rev. Lett. 1998, 80, 3089. Liu, X. Y.; et al. J. Cryst. Growth 2000, 208, 687.). Yet it remains unanswered why each crystallite appears with specific orientation and obeys a strict order. Here we report an in-depth study of the origin of the long-range correlation of the crystallographic orientations in the aggregate investigated by means of micro-X-ray-diffraction, atomic force microscopy, and in-situ optical observation. The experimental data suggest that the topographic regularity of the aggregate arises from the consecutive rotation of the crystallographic orientation in the nucleation-mediated growth. This effect may occur when nucleation takes place in a region with inhomogeneous surface tension, and may help us to understand the long-range ordering effect in aggregating crystallites.

The morphology of iron electrodeposit is shown to relate closely to the pH of the electrolyte solution. Macroscopically, depending on the strength of the interbranch convection, which is associated with the concentration of H3O1 in the electrolyte, the deposit morphology varies from treelike pattern to meshlike pattern and dense-branching morphology. Microscopically the deposit is ramified and dense-branching at lower concentration of H3O1, while it becomes relatively smooth and stringy at higher H3O1 concentration. The symmetry of the convective vortices on the two sides of the growing tip is observed to decide the growth behavior of the tip. We suggest that H3O1 influences the pattern formation and pattern selection in the electrodeposition of iron from FeSO4 solution by either initiating interbranch convection or changing the effective interfacial energy of the deposit and the electrolyte.