Ultrafast optical emission of nanodiamond induced by laser excitation

The ultrafast optical emission of nanosized (∼5nm) crystallites has been detected under the picosecond (ps) laser excitation of 300nm through ultrafast fluorescence spectroscopy. This optical emission, photoluminescence (PL), induced at a laser wavelength of 300nm confines blue light. The ultrafast PL spectrum deconvoluted by a Monte Carlo method shows that two fast emission processes with decaytimes of 60 and 350ps. This type of ultrafast emission has not been observed under the same experimental conditions from the samples of a natural single crystal and an impure natural single crystal diamond. The mechanism responsible for this visible ultrafast emission is proposed by taking into account the effect of surface states and large surface-to-volume ratio of nanoparticles. All of these findings demonstrate the feasibility of using large band-gap nanomaterials to generate ultrafast optical emission at various wavelengths.