Onion-like carbon nanoparticles generated by multiple laser irradiations on laser-ablated particles

A one-step process to synthesize onion-like carbon nanoparticles at room temperature under atmospheric pressure was developed. Periodic pulsed laser irradiation of carbon nanoparticles confined in the cavity of a carbon target rod induces drastic changes to their structure, changing them from amorphous to ordered concentric graphitic shells. The size distribution of gas-borne nanoparticles measured by a scanning mobility particle sizer showed the mean mobility diameter decreased from 83 nm to 18 nm as a result of restructuring of carbon agglomerates. Polyhedral and unagglomerated nanoparticles with shell structures composed of multiple graphene sheets were observed by a transmission electron microscopy.