Spectroscopic Characterization of Flame-Generated 2-D Carbon Nano-Disks

In this work we produce atomically thin carbon nanostructures which have a disk-likeshape when deposited on a substrate. These nanostructures have intermediate characteristicsbetween a graphene island and a molecular compound and have the potentiality to be used eitheras they are, or to become building blocks for functional materials or to be manipulated andengineered into composite layered structures.The carbon nanostructures are produced in a premixed ethylene/air flame with a slightexcess of fuel with respect to the stoichiometric value. The size distribution of the producedcompounds in aerosol phase has been measured on line by means of a differential mobilityanalyzer (DMA) and topographic images of the structures deposited on mica disks were obtainedby Atomic Force Microscopy. Raman spectroscopy and XPS have been used to characterize theirstructure and the electronic and optical properties were obtained combining on-linephotoionization measurements with Cyclic Voltammetry, light absorption andphotoluminescence.When deposited on the mica substrate the carbon compounds assume the shape of anatomically thin disk with in plane diameter of about 20 nm. Carbon nano-disks consist of anetwork of small aromatic island with in plane length, La, of about 1 nm. Raman spectraevidence a significant amount of disorder which is in a large part due to the quantumconfinement in the aromatic islands. Nano-disks contain small percentage of sp3 and the O/Cratio is lower than 6%. They furthermore present interesting UV and visible photoluminescenceproperties.