title: Dominant luminescence is not due to quantum confinement in molecular-sized silicon carbide nanocrystals.
abstract: Molecular-sized colloid silicon carbide (SiC) nanoparticles are very promising candidates to realize bioinert non-perturbative fluorescent nanoparticles for in vivo bioimaging. Furthermore, SiC nanoparticles with engineered vacancy-related emission centres may realize magneto-optical probes operating at nanoscale resolution. Understanding the nature of molecular-sized SiC nanoparticle emission is essential for further applications. Here we report an efficient and simple method to produce a relatively narrow size distribution of water soluble molecular-sized SiC nanoparticles. The tight control of their size distribution makes it possible to demonstrate a switching mechanism in the luminescence correlated with particle size. We show that molecular-sized SiC nanoparticles of 1-3 nm show a relatively strong and broad surface related luminescence whilst the larger ones exhibit a relatively weak band edge and structural defect luminescence with no evidence of quantum confinement effect.
authors.affiliation: Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, PO. Box 49, H-1525 Budapest, Hungary. beke.david@wigner.mta.hu gali.adam@wigner.mta.hu.
authors.forename: David
authors.initials: D
authors.lastname: Beke
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szekrényes
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Czigány
authors.forename: Katalin
authors.initials: K
authors.lastname: Kamarás
authors.forename: Ádám
authors.initials: Á
authors.lastname: Gali