Enhanced sensing properties of cobalt bis-porphyrin derivative thin films by a magneto-plasmonic-opto-chemical sensor

This work reports on the spectroscopic properties and gas sensing performances of cobalt bis-porphyrin derivative ((Co-H)Por) in a thin films form obtained by Langmuir-Schäfer (LS) method towards Volatile Organic Compounds (VOCs) and an oxidizing gas in a Magneto-Optical Surface Plasmon Resonance (MO-SPR) configuration. In particular the optical and spectroscopic properties of (Co-H)Por multilayers deposited onto proper Au/Co/Au magneto-plasmonic (MP) transducers were inspected in dry air conditions and after exposure to different analyte gas concentrations. The molecular organization of these thin films deposited by Langmuir-Schäfer technique has been investigated and a comparison between the MOSPR experimental data and simulation has been also reported. In order to validate our experimental results and obtain further insight into the physical mechanism of interaction between the organometallic molecules and magneto plasmonic nanostructured systems, numerical simulations based on Finite Element Method (FEM) techniques, have been performed. The optical and magneto-optical properties of these hybrid systems have been theoretically analyzed to confirm the experimental outcomes. Finally, a peculiar sensitivity of the MOSPR sensing probe in respect to investigated analytes has been recorded.