Directional surface plasmon-coupled emission of CdTe quantum dots and its application in Hg(ii) sensing

Abstract

We investigated the surface plasmon-coupled emission (SPCE) of CdTe quantum dots (QDs) and developed an SPCE-based quenchometric sensor for Hg(II) ion sensing. CdTe QDs directly synthesized in aqueous solution were attached to a 50 nm-thick Au film through layer-by-layer assembly. The directional emission of the CdTe QDs on the prism side from the surface plasmon coupling was completely p-polarized and observed at a fixed angle of 48.5°, which was consistent with theoretical calculations. An SPCE-based quenchometric sensor for Hg(II) ion sensing was established based on the quenching effect of Hg(II) ions on the fluorescence emission of CdTe QDs. As expected, the SPCE-based sensor enlarged the response range and was more sensitive than that based on free-space detection as a result of the high light-collection efficiency of SPCE. QDs with excellent properties combined with SPCE technology have great potential in detecting analytes at low concentration levels.