Abstract
Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.
Highlights
Since the early studies on surface-enhanced Raman scattering (SERS), amorphous carbon has been known as a potential contaminant that generates intense, broad background signals [1,2]
Amorphous carbon is frequently observed in SERS measurements at low molecular concentrations, so far there is no complete understanding of the circumstances of its formation
DNA-coated gold or silver nanoparticles of 60 nm diameter were assembled into dimers by triangular DNA origami scaffolds (Figure 1A)
Summary
Since the early studies on surface-enhanced Raman scattering (SERS), amorphous carbon has been known as a potential contaminant that generates intense, broad background signals [1,2]. The present study discusses the formation of amorphous carbon on DNA origami-assembled plasmonic nanostructures for several different experimental conditions. 170 × 190 μm with 60 nm silver dimers, demonstrating the gradual increase of the amorphous carbon indicate that decreasing the irradiation power density is more efficient in reducing amorphous carbon signal
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