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激发波长依赖发光是碳基荧光材料中有趣的光学性质之一,其在不同激发波长下呈现的多彩发光对某些实际应用很重要.本文以氧化石墨烯为碳源,采用酸氧化法制备了尺寸约为3~5nm的少层石墨烯量子点(GQDs),然后将其与乙二胺(EDA)在160℃下进行水热反应,得到了石墨烯边缘氮掺杂的石墨烯量子点(NGQDs).采用傅立叶变换红外光谱(FTIR)证实了N-GQDs中酰胺键和胺C-N键的形成.GQDs的吸收主要来自C=C的π-π*跃迁(265nm)和C-O相关的n-π*跃迁(340nm),而N-GQDs中出现了C(=O)NHR相关的新能级(386nm).GQDs荧光峰随着激发光波长的移动Δλem/Δλex呈现线性变化,斜率约为0.43,而N-GQDs的Δλ_(em)/Δλ_(ex)出现两段线性变化,激发波长在420nm以后斜率增大到0.78,表明C(=O)NHR相关的荧光偶极子具有更强的激发波长依赖性发光特性.
Excitation wavelength-dependent luminescence is one of the interesting optical properties of carbon-based fluorescent materials, and its colorful luminescence under different excitation wavelengths is very important for some practical applications.In this paper, graphene oxide as a carbon source, prepared by acid oxidation (GQDs) with a size of about 3 ~ 5nm, and then hydrothermally reacted with ethylenediamine (EDA) at 160 ℃ to obtain graphene QDs ( NGQDs) .The formation of amide bond and amine CN bond in N-GQDs was confirmed by Fourier transform infrared spectroscopy (FTIR) .The absorption of GQDs mainly came from the π-π * transition of C = C (265nm) and the n-π * Transition (340nm), and the new energy level (386nm) related to C (= O) NHR appeared in N-GQDs.The fluorescence peak of GQDs showed a linear change with the shift of the excitation wavelength Δλem / Δλex with a slope of about 0.43, However, the Δλ_ (em) / Δλ_ (ex) of N-GQDs showed two linear changes, and the slope increased to 0.78 after the excitation wavelength of 420nm, indicating that the fluorescence dipole of C (= O) NHR had a stronger excitation wavelength Dependent luminescence properties.