Aqueous CdTe quantum dots (QDs) were synthesized employing thiols as stabilizing ligands and their emission wavelengths could be tuned by controlling the reflux time. Surface plasmon-coupled emission (SPCE) properties of multicolor CdTe QDs were studied by using a laboratory-built multifunctional spectrofluorimeter. To fabricate a CdTe QDs-doped complete film onto the surface of continuous thin metal films, CdTe QDs were spin-coated at 3000 r/min with poly(vinyl alcohol) (PVA) solution of various concentrations. For SPCE measurements, the spin-coated slides were attached to a semi-cylindrical prism made of fused silica with a refractive-index-matching fluid and then positioned on a precise rotary stage that allowed for excitation and emission observation at any angle relative to the vertical axis of the stage. For excitation, we used the reverse Kretschmann (RK) configuration and the incident light was normal to the sample interface. The spectra were measured using a monochromator equipped with a photomultiplier tube. The experimental results showed CdTe QDs located nearby continuous thin metal film could be excited using either blue (473 nm) or green (532 nm) laser as a result of their broad excitations and their emissions resulting from the surface plasmon coupling were strongly directional, highly polarized and closely related to sample thickness. Because of the wavelength-resolution property of SPCE, CdTe QDs with different emission wavelengths were found to emit at different fixed angles, longer wavelengths corresponding to smaller angles. The free space emission spectra of 720 nm and 630 nm CdTe QDs in a mixture were overlapped and could not be separated at any detection angle. However, owing to the unique wavelength resolution ability of SPCE, the spectra of 720 nm and 630 nm CdTe QDs were obtained at 43? and 51? on the prism side, respectively. The determination of each component of the mixtures of CdTe QDs was achieved by changing the detection angle to avoid spectral overlap. Therefore, QDs are ideal fluorophores for SPCE in high-throughput, multiplex analysis application.

Key words: surface plasmon-coupled emission (SPCE), CdTe quantum dots, broad excitation, continuous tunable emissions, wavelength resolution