Fluorescence Quantum Effect of Carbon Microsphere

Carbon dots(C-Dots),an advanced fluorescent nanomaterial,have good prospects for development and application.Based on their advantages over quantum dots(QDs) and other fluorescent nanoparticles,C-dots could replace QDs in the scientific fields such as solar cells,luminescent device and optical biomarkers.Carbon microspheres(CMSs) were prepared by chemical vapor deposition using acetylene as carbon resource;then,CMSs were modified by chitosan(CS) and SiO2;finally,the fluorescence of CMSs and their composites were studied under ultraviolet irradiation(excited at 254 nm),in which the effects of solvent and concentration of suspension were considered.Field emission scanning electron microscopy,Fourier transformation infrared spectrometry and fluorescence spectrometry were employed to characterize the morphology and structure of the samples.The results show that as-synthesized CMSs,oxidized CMSs,CS/CMSs and SiO2/CMSs with different suspension concentrations emitted different fluorescence in organic solvents(ethanol and tetrachloromethane) and water.With increasing solvent polarity,the fluorescence color changed from purple to yellow,and with increasing concentration,the fluorescence color gradually deepened and finally led to fluorescence quenching at high concentration.