Department of Engineering Science and Mechanics,
The Pennsylvania State University, University Park, PA 16802-6812, USA
Beaded SiC nanorings (inner size: 3-10nm; outer size: 9-20 nm) can be synthesized at room temperature by reactive laser ablation of a silicon wafer in an organic medium combined with a subsequent selective chemical etch. The prepared SiC nanorings exhibit apparent quantum confinement effects, emitting strong violet-blue photoluminescence under ultraviolet excitation. More importantly, an anomalous red spectral shift ascribed to collective effects between surface structures and quantum confinement is observed. This is the first experimental confirmation that surface reconstruction and termination dominates the optical properties of SiC NCs below a threshold diameter of 3 nm determined by theoretical calculations. The photoluminescence tunability, biocompatibility, nontoxicity, and chemical stability make SiC nanorings excellent candidates for applications in biomedicine (e.g., bio-imaging) and optical devices operating under extreme conditions (e.g., high-temperature, high-pressure and/or highly corrosive environments). In principle, the fabrication technique presented here could also be extended into the fabrication of other carbide, nitride, and carbonitride nanostructures.