Multicolor directional surface plasmon-coupled chemiluminescence

In reports over the past several years, we have demonstrated the efficient collection of optically excited fluorophore emission by its coupling to surface plasmons on thin metallic films, where the coupled luminescence was highly directional and polarized. This phenomenon is referred to as surface plasmon-coupled emission (SPCE). In this current study, we have extended this technique to include chemiluminescing species and subsequentially now report the observation of surface plasmon-coupled chemiluminescence (SPCC), where the luminescence from chemically induced electronic excited states couples to surface plasmons in thin continuous metal films. The SPCC is highly directional and predominantly p-polarized, strongly suggesting that the emission is from surface plasmons instead of the luminophores themselves. This indicates that surface plasmons can be directly excited from chemically induced electronic excited states and excludes the possibility that the plasmons are created by incident excitation light. This phenomenon has been observed for a variety of chemiluminescent species in the visible spectrum, ranging from blue to red, and also on a variety of metals, namely, aluminum, silver, and gold. Our findings suggest new chemiluminescence sensing strategies on the basis of localized, directional, and polarized chemiluminescence detection, especially given the wealth of assays that currently employ chemiluminescence-based detection.