Up-converted emission of colloidal nanocrystals containing dendrimers

The spectroscopic and microscopic investigation of polystyrene nanocrystals containing dodecanamide-modified poly(propyleneimine) dendrimers was performed. Nearly monodisperse colloidal particles have diameters of 60 nm. Up-converted emission in the deep blue around 430 nm was observed upon excitation with lower-energy photons from 480 to 540 nm. The intersystem crossing time constant was estimated to be 11 ps through an up-converted emission measurement.