Single Molecule Surface-Enhanced Raman Spectroscopy without Nanogaps

• Published in: The journal of physical chemistry letters Vol. 4; no. 19; pp. 3206 - 3210
• Main Authors: Zrimsek, Alyssa B, Henry, Anne-Isabelle, Van Duyne, Richard P
• Format: Journal Article
• Language: English
• Published: American Chemical Society 03.10.2013
• Subjects: Plasmonics, Optical Materials, and Hard Matter
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/jz4017574

We provide conclusive proof of single molecule (SM) detection by surface-enhanced Raman spectroscopy (SERS) for discrete Ag triangular nanopyramids prepared via nanosphere lithography (NSL). While the observation of SMSERS has been well-demonstrated using various chemically synthesized nanoparticle substrates, they have a high degree of polydispersity in shape, size, and aggregation state resulting in an interest to develop more reproducible and uniform nanoparticles. Here triangular-based nanopyramids were characterized by scanning electron microscopy to confirm their geometry and interparticle spacing. Then the isotopologue approach with Rhodamine 6G was used to conclusively prove SM sensitivity for the individual nanoparticles. NSL’s straightforward, simple fabrication procedure produces large active arrays. Furthermore, the tunable localized surface plasmon resonance makes NSL prepared substrates effective for the detection of resonant molecules by SMSERS.