Figure 4
From: Metal hierarchical patterning by direct nanoimprint lithography
Biomimicking.
(a) SEM images of metallic rice leaf pattern (after heat treatment) with primary lines of 1.7 μm and secondary pillars of 90 nm and corresponding height of 170 nm and 60 nm, respectively, marked in the AFM profiles.(b) The contact angles in parallel and perpendicular direction of the metallic rice leaf lines differ due to anisotropic wetting. After hexadecanethiol absorption, the contact angle is increased in both directions. (c) Surface enhanced Raman spectrum of a monolayer of the adsorbed thiol molecules on Pd rice leaf compared with that from a drop of neat thiol. The peak observed can be assigned to ν(C-S)trans stretch. The signal from the monolayer is of similar intensity as the bulk, due to SERS activity of the metallic rice leaf structure.
