Fluorescence response from the surface states of nitrogen-doped carbon nanodots: evidence of a heterogeneous population of molecular-sized fluorophores†,Photochemical & Photobiological Sciences

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Fluorescence response from the surface states of nitrogen-doped carbon nanodots: evidence of a heterogeneous population of molecular-sized fluorophores†
Photochemical & Photobiological Sciences ( IF 2.7 ) Pub Date : 2018-10-01 00:00:00 , DOI: 10.1039/c8pp00077h
Nabaruna Basu _{1,

2,

3,

4} , Debabrata Mandal _{1,

2,

3,

4}

Affiliation

Fluorescent Nitrogen-doped Carbon Nanodots (NCDs) of ∼4 nm diameter were prepared by acid-driven microwave irradiation of DMF solvent. Spectroscopic studies of the NCDs demonstrated that excitation of the carbon core did not contribute any fluorescence emission. Instead, the emission originated exclusively from the surface states. The fluorescence featured a prominent red edge excitation shift (REES), while changing the excitation wavelength over ∼0.5 eV indicated the emergence of different emitter species in the temporal evolution of fluorescence. These results combined to indicate a large degree of heterogeneity in the population of these surface-localized emitters, so that working with different excitation energies produced different sets of excited surface fluorophores that evolved independently of each other. Fluorescence anisotropy dynamics in the NCDs was attributable to the reorientational motion of the surface fluorophores which was decoupled from the rotational diffusion of the carbon core of the NCD. The anisotropy decay rates revealed that the fluorophores had size comparable to typical organic fluorophores, irrespective of excitation energy.

中文翻译：

氮掺杂碳纳米点表面状态的荧光响应：分子大小荧光团异质种群的证据†

通过酸驱动的DMF溶剂微波辐照制备直径约4 nm的荧光氮掺杂碳纳米点（NCD）。NCD的光谱研究表明，碳核的激发没有任何荧光发射。相反，发射完全源自表面状态。荧光具有显着的红边激发位移（REES），而在〜0.5 eV范围内改变激发波长则表明在荧光的时间演化中出现了不同的发射体。这些结果结合起来表明这些表面定位的发射体在很大程度上具有异质性，因此使用不同的激发能可以产生不同的激发表面荧光团，它们彼此独立地进化。NCD中的荧光各向异性动力学归因于表面荧光团的重新定向运动，该运动与NCD碳核的旋转扩散不相关。各向异性衰减率表明，荧光团的大小与典型的有机荧光团相当，而与激发能量无关。

更新日期：2018-10-01

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