Ternary cadmium sulphide selenide quantum dots as new scintillation materials

Monodisperse, highly luminescent, zinc blende, cadmium sulphide selenide (CdS_xSe_1-x, x=mole fraction of sulphur) quantum dots (QDs) were prepared in gram scales in the particle size range 2.6-4.3 nm. With the varying S and Se contents, emission wavelengths of CdS_xSe _1-x QDs were tuned from 439 to 581 nm (λexc.=370 nm). QDs were well dispersed in organic solvents and optically transparent plastic scintillators made with up to 10 wt-%QDs in polyvinyltoluene (PVT) were prepared. The result from alpha particle detection indicated the wavelengths match with the sensitivity of the photomultiplier tube. Pulse height peaks of (CdS_xSe_1-x with the wavelength of emission from 439 to 482 nm, appeared around 0.35 (channel no./amplifier gain), with different photon counts. No pulse height peak was observed with QDs that emitted at 505 nm or longer wavelengths. Under studied conditions, CdS_0.95Se _0.05 was found to be the most efficient scintillator.