Emission enhancement metal-enhanced chemiluminescence

Based on our research laboratory s observations of MEF from metals other than silver, MEC from chromium, coppo, nickel and zinc was also studied. Figure 1. 12 shows the enhancement factors for green chemiluminescence from diese metals with various thicknesses. A typical enhancement factor of 2-3-fold is observed from all metal surfaces, vdiich implies that chemically excited states can couple to these plasmon resonant metal particles. It is interesting to note that the chemiluminescence emission is dependent on the amount of reactants in the solution and diminishes once one of the reactants is used up. To test viiether the remainder of the inactive chemiluminescent dye can be excited with an external light source and still emit luminescence, additional experiments were undertaken where the chemiluminescence solution was excited with a laso at 473 nm. Interestingly, the inactive chemiluminescence dye can be optically excited and still emit luminescence with enhancement factors similar to the chemically excited conditions being observed. A detailed investigation of MEC from different metals is currently underway and will be reported in due course. 

The basis of this analysis is said to be the formation of a peroxy phosphate compound (the Schoenemann reaction [49]). Oxidation of an amine such as 3,3 -dimethoxy benzidine or indole in a colorimetric reaction, or in the present case luminol with the emission of light then follows. Lucigenin does not work in this assay although it has been claimed as useful in the analysis of the nerve gas Tabun (5) [46]. Related insecticides such as Isopestox behave similarly [46-48]. Sensitivity can be improved by addition of chloride ion [52], enhancing the light yield, or by suppression of background chemiluminescence by complexation of trace transition metals by EDTA. 

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