Nanopatterning Gold by Templated Solid State Dewetting on the Silica Warp and Weft of Diatoms

Figure 1

TEM image of exfoliated Nitzschia palea frustules. The upper valve half is the hypothecum, where the sternum of the raphe (slit) is visible as a thickened dark band. The bottom valve half epithecum shows the mating portion of the sternum. The raphe involves a thickened region of silica from which silica costae emanate to give a “warp and weft” structure to the basal silica plate (see AFM images, Figure 2). The nearly rectangular foramina (pore passageways) are distributed on a roughly rhombic lattice. The foramina are partially occluded by a perforated sieve plate (velum) that is not visible at this magnification. Cribellar pores in the sieve plate are arranged in roughly octagonal fashion and have diameters of about 20 nm. Insert is the Fourier transform of the array of pores, confirming the rhombohedral arrangement. The scale bar is 2 μm.