we also thank sandra hirzberger and alexey shavel for assisting with the powder xrd measurements and chemical syntheses respectively .
nm appreciates the financial support provided by german academic exchange service and japan society for the promotion of science .
 judicious selection of the amount of surfactant during synthesis enables a drastic increase in the photoluminescence efficiency of aqueous cdte nanocrystals ( ncs ) stabilized by thioglycolic acid ( tga ) . 
 elemental determination of the ncs was undertaken to identify the origin of this effect . 
 the molar ratio of ( te + s ) to cd approached unity when the optimum amount of tga was used during synthesis , whereas the number of s atoms originating from tga molecules in one nc ( 2.6 nm of diameter ) remained unchanged at 90  3 . 
 this indicates that the core lattice composition at the beginning of synthesis , rather than the surface conditions , affects the photoluminescence efficiency of the ncs even after prolonged refluxing . 
Acknowledgements