Fluorescence Dynamics in BSA-Protected Au25 Nanoclusters
Fluorescence Dynamics in BSA-Protected Au25 Nanoclusters
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DOI：
10.1021/jp305902w
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发表时间：
2012-09-06
影响因子：
3.7
通讯作者：
Tang, Jau
中科院分区：
文献类型：
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作者：
Wen, Xiaoming;Yu, Pyng;Tang, Jau
荧光Au-25纳米团簇由于其独特的性质和潜在的应用前景，近年来引起了广泛的研究兴趣。尽管它们的合成方法和应用发展取得了重大进展，但荧光的起源和潜在的机制仍然不清楚。在这项工作中，我们通过时间分辨光致发光和瞬态吸收技术研究了bsa保护的Au-25纳米团簇的荧光动力学，涵盖皮秒到微秒的时间尺度。我们在这里证明了红色荧光包括提示荧光和热激活的延迟荧光，后者更占优势。三重态和单重态之间有一个30 meV的小能隙，这是由我们的温度依赖的时间分辨荧光测量确定的。此外，由于Au-25 NCs和BSA之间的相互作用，我们阐明了该体系中2.34 eV的吸收带对应于HOMO-LUMO跃迁。我们还证明了从高激发态到LUMO存在有效的弛豫途径。
Fluorescent Au-25 nanoclusters recently have drawn considerable research interest due to their unique properties and potential applications. Despite significant advances in their synthesis methods and application development, the origin of the fluorescence and underlying mechanism still remain unclear. In this work we investigate the fluorescence dynamics in BSA-protected Au-25 nanoclusters by time-resolved photoluminescence and transient absorption techniques covering picosecond to microsecond time scales. We demonstrate here that the red fluorescence consists of both prompt fluorescence and thermally activated delayed fluorescence, and the latter is more dominant. A small energy gap of 30 meV between the triplet and the singlet states was determined from our temperature-dependent time-resolved fluorescence measurement. Moreover, we elucidate that the absorption band at 2.34 eV corresponds to the HOMO-LUMO transition in this system due to the interaction between Au-25 NCs and BSA. We also show that an effective relaxation pathway exists from the higher excited state to the LUMO.