title: Cellphone Monitoring of Multi-Qubit Emission Enhancements from Pd-Carbon Plasmonic Nanocavities in Tunable Coupling Regimes with Attomolar Sensitivity.
abstract: We demonstrate for the first time the tuning of qubit emission based on cavity engineering on plasmonic silver thin films. This tunable transition from weak to strong coupling regime in plasmon-coupled fluorescence platform was achieved with the use of palladium nanocomposites. In addition to our recently established correlation between Purcell factor and surface plasmon-coupled emission enhancements, we now show that the qubit-cavity environment experiences the Purcell effect, Casimir force, internal fano resonance, and Rabi splitting. Finite-difference time-domain simulations and time correlated single photon counting studies helped probe the molecular structure of the radiating dipole, rhodamine-6G, in palladium-based nanocavities. The sensitivity of the qubit-cavity mode helped attain a DNA detection limit of 1 aM (attomolar) and multianalyte sensing at picomolar concentration with the use of a smartphone camera and CIE color space. We believe that this low-cost technology will lay the groundwork for mobile phone-based next-gen plasmonic sensing devices.
authors.affiliation: Plasmonics Laboratory, Department of Chemistry, Sri Sathya Sai Institute of Higher Learning , Prasanthi Nilayam, Puttaparthi, Anantapur, Andhra Pradesh, India 515134.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Srinivasan
authors.affiliation: Plasmonics Laboratory, Department of Chemistry, Sri Sathya Sai Institute of Higher Learning , Prasanthi Nilayam, Puttaparthi, Anantapur, Andhra Pradesh, India 515134.
authors.forename: Anupam Kumar
authors.initials: AK
authors.lastname: Manne
authors.affiliation: Plasmonics Laboratory, Department of Chemistry, Sri Sathya Sai Institute of Higher Learning , Prasanthi Nilayam, Puttaparthi, Anantapur, Andhra Pradesh, India 515134.
authors.forename: Sai Gourang
authors.initials: SG
authors.lastname: Patnaik
authors.affiliation: Plasmonics Laboratory, Department of Chemistry, Sri Sathya Sai Institute of Higher Learning , Prasanthi Nilayam, Puttaparthi, Anantapur, Andhra Pradesh, India 515134.
authors.forename: Sai Sathish
authors.initials: SS
authors.lastname: Ramamurthy
keywords: DNA detection; cellphone; coupling regime; palladium nanocomposites; qubit; surface plasmon-coupled emission