Figure 5
From: Physically unclonable functions taggant for universal steganographic prints
Distribution of the nanobeacons: (a) Optical photograph of the paper surface to which we applied aqueous ink that included nanobeacons. (b) Scanning electron microscopy image of Au nanoparticle aggregates included in the stealth nanobeacon. Surface-enhanced Raman spectroscopy (SERS) mappings of (c) 1 mm × 1 mm and (d) 100 μm × 100 μm at 1600 cm−1. (e,f) SERS spectra for the locations in the Raman mapping shown in (d). The inset in (f) shows a SERS mapping at (d) at 1400 cm−1.
