Directional, Broad, and Fixed Angle Surface Plasmon Coupled Fluorescence from Iron Thin Films.

Fixed angle surface plasmon coupled fluorescence (SPCF) from iron thin films is demonstrated for the first time. The optimum thickness of the iron thin films was determined to be 15 nm using Fresnel calculations. The angles of minimum reflectivity for light at 496-814 nm were predicted to occur at a fixed and broad range of angles of 60-70°. Experimental corroboration of these predictions were undertaken by employing fluorescein isothiocyanate (emission peak at 517 nm), rhodamine B (580 nm), zinc phthalocyanine (710 nm), and IR 780 dye (814 nm). SPCF emission from all four fluorophores was directional, p-polarized, and observed at a fixed angle of ∼65°.