Figure 1

$500\times 500\mathrm{nm}$ AFM images—acquired at a scan rate of about $7\mathrm{\text{lines}}/\mathrm{s}$—of hemicylindrical surfactant aggregates formed on HOPG in a 10 mM CTAC solution. Images (a)–(d) show the same area at intervals of 70 s. After reaching thermal equilibrium, the drift is less than 1 nm per min and time-lapse imaging of a given region is possible. Panel (c) also defines the three $\alpha$ and the three $\beta$ directions, parallel and perpendicular to the symmetry axes of graphite. A MultiMode/NanoScope IIIa AFM, Veeco Instruments, Santa Barbara, CA, was used.Reuse & Permissions

Figure 2

Diagrams: A CTAC molecule lying parallel to a symmetry axis of graphite, $\alpha$ orientation (left). The $\beta$ orientation (right) is perpendicular to the symmetry axis on the same graphite surface. Curves: Calculated van der Waals energies of the molecule on a graphite surface. The atoms are represented by their respective van der Waals radii. The molecule was moved laterally on the graphite surface so as to sample different positions with the same orientation. The energetic difference between two orientations is about 22 meV. Note that adsorption of surfactant in the $\alpha$ orientation corresponds to micelle alignment in $\beta$ orientation; thus the constituent molecules of a micellar hemicylinder are oriented perpendicular to its axis.Reuse & Permissions

Figure 3

The relative probability relation for hemicylindrical micelles ($a=2.0\mathrm{nm}$) of different lengths adsorbed on graphite in water. The inset is a schematic orientation diagram. Here $x$ and $y$ denote distances parallel and perpendicular to one of the symmetry axes of HOPG. The orientation of the rod is given by the director, $\mathbf{p}$, lying parallel to the long axis of the assembly. A large relative probability represents a strong tendency for alignment perpendicular to the symmetry axis of the graphite.Reuse & Permissions