Investigation on the Relationship Between Carbon Cores and Fluorescence Moieties by Measurement of Fluorescence Anisotropy of CDs with Different Sizes

Abstract

Carbon dots(CDs) have been considered as a marvellous photoluminescence(PL) material, and their PL mechanism remains debatable. The carbon core, as an essential part of CDs, apparently plays an intricate role in the PL of CDs. However, the influence of the core on the PL and the relationship between the core and fluorescence moiety are still unclear. Here, we investigated the influence of carbon cores with different sizes on the rotational motion of fluorescence moieties to determine the relationship between carbon cores and fluorescence moieties. CDs with different size distributions were synthesized by controlling carbonization time. The core sizes and rotational correlation time(RCT) of the CD samples were measured by transmission electron microscopy(TEM) and fluorescence anisotropy measurement, respectively. And the rotating unit radius were calculated from the RCT. The experimental results show that the rotational motion of the fluorescence moiety is independent of the carbon core sizes and it possesses total rotational freedom. This work is helpful for understanding the connection between the carbon core and fluorescence moiety and its influence on the PL properties of CDs.