Laser Induced Popcorn-like Conformational Transition of Nano-diamond as a Nanoknife

Nanodiamond (ND) is surrounded by layers of graphite on its surface. This unique structure feature creates unusual fluorescence spectra, which can be used as an indicator to monitor its surface modification. Meanwhile, the impurity, nitroso (C-N=O) inside the ND can be photolyzed by two-photon absorption, releasing NO to facilitate the formation of a sp3 diamond structure in the core of ND and transforming it into a sp2 graphite structure. Such a conformational transition enlarges the size of ND from 8 nm into 90 nm, resulting in a popcorn-like structure. This transition reaction may be useful as nano-knives in biomedical application.