Purcell Factor: A Tunable Metric for Plasmon-Coupled Fluorescence Emission Enhancements in Cermet Nanocavities

• Published in: Journal of physical chemistry. C Vol. 120; no. 5; pp. 2908 - 2913
• Main Authors: Srinivasan, Venkatesh, Ramamurthy, Sai Sathish
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.02.2016
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b11311

We demonstrate an important approach to correlate Purcell factor (PF) and surface plasmon-coupled emission (SPCE) enhancements with the use of finite-difference time-domain (FDTD) simulations and time-correlated single-photon counting (TCSPC) studies of a radiating dipole in cermet nanocavities. We observed >50-fold fluorescence enhancement with high directionality and polarization of Rhodamine 6G (Rh6G) emission trapped in the nanocavity created between the titanium-based ceramic nanoparticle and metallic silver thin film. Compositional variation with hybrid nanoparticles, TiC0N1 (TiN), TiC0.5N0.5 (TiCN), and TiC1N0 (TiC), brought about enhanced PFs and tunable fluorescence enhancements that were used for mobile-phone-based detection of tryptophan with nanomolar sensitivity. We hope that this study opens the door to next-gen plasmonics with the ability to tune and enhance the hot-spot electromagnetic field intensity of alternative plasmonic materials, as hybrid synergy spacers in the SPCE platform.