二维Bi2Se3晶体对罗丹明6G分子的荧光猝灭效应研究

Fluorescence Quenching Effect of Rhodanmine 6G on Two-Dimensional Bi_2Se_3 Crystals

首次研究了拓扑绝缘体Bi2Se3二维晶体对其表面吸附的罗丹明6G分子的荧光猝灭效应,证明薄层Bi2Se3可以有效猝灭罗丹明6G分子的荧光,且随Bi2Se3二维晶体的厚度从单层增加到8层,荧光猝灭效应增强,并初步探讨了其荧光猝灭机理.

As a novel quantum material, two-dimensional crystal of Bi2Se3 is a typical topological insulator with an insulating bulk gap and gapless edges or surface states, which has created new opportunities for spintronics and low-dissipation electric transport. For the first time, we studied the fluorescence quenching effect of Rhodanmine 6G molecules on two-dimensional crystals of Bi2Se3 with the thickness ranged from 1 layer to 8 layers. Atomically-thin, high-quality two-dimensional crystals of Bi2Se3 with different thicknesses down to monolayer were firstly grown on mica substrates via van der Waals epitaxy. Typically, its domain size is about tens or several tens micrometers, providing a good platform for studying the thickness-dependent chemical and physical properties of two-dimensional Bi2Se3 crystals. Besides, as fluorescence-probe molecules with high fluorescence quantum yield, a uniform and continuous film of Rhodamine 6G molecules were deposited onto the surface of mica substrate and two-dimensional Bi2Se3 crystals by vacuum evaporation, on which adsorption of almost equal number of Rhodamine 6G molecules was achieved revealed by atomic force microscopy characterization. Subsequently, the measurements of fluorescence spectroscopy were conducted on the Horiba-Jobin Yvon Labram HR800 micro Raman spectrometer with a spatial resolution about 1 μm. Excited by 514.5 nm Ar＋ laser, the fluorescence signal from 520 nm to 640 nm of Rhodanmine 6G molecules on different surfaces was collected under the same condition. It was found that the atomically-thin Bi2Se3 crystals can quench the fluorescence of adsorbed Rhodamine 6G molecules. Meanwhile, the thicker Bi2Se3 crystals show more obvious quenching ability to Rhodanmine 6G molecules. In the end, a possible quenching mechanism of fluorescence resonance energy transfer was suggested. According to the UV-Vis spectroscopy of two-dimensional crystals of Bi2Se3, the absorption spectroscopy of Bi2Se3 showed a large spectral overlap with the emission fluorescent of Rhodanmine 6G, which is the key to fluorescence resonance energy transfer.