Laboratoire d'Electronique Moléculaire, Organique et Hybride (LEMOH), INAC/SPrAM UMR 5819 (CEA-CNRS-UJF), CEA Grenoble, 17, rue des Martyrs, F-38054 Grenoble, France.
ACS Nano. 2012 Oct 23;6(10):9033-41. doi: 10.1021/nn303150j. Epub 2012 Sep 28.
We have analyzed the decays of the fluorescence of colloidal CdSe quantum dots (QDs) suspensions during dilution and titration by the ligands. A ligand shell made of a combination of trioctylphosphine (TOP), oleylamine (OA), and stearic acid (SA) stabilizes the as-synthesized QDs. The composition of the shell was analyzed and quantified using high resolution liquid state 1H nuclear magnetic resonance (NMR) spectroscopy. A quenching of the fluorescence of the QDs is observed upon removal of the ligands by diluting the stock solution of the QDs. The fluorescence is restored by the addition of TOP. We analyze the results by assuming a binomial distribution of quenchers among the QDs and predict a linear trend in the time-resolved fluorescence decays. We have used a nonparametric analysis to show that for our QDs, 3.0 ± 0.1 quenching sites per QD on average are revealed by the removal of TOP. We moreover show that the quenching rates of the quenching sites add up. The decay per quenching site can be compared with the decay at saturation of the dilution effect. This provides a value of 2.88 ± 0.02 for the number of quenchers per QD. We extract the quenching dynamics of one site. It appears to be a process with a distribution of rates that does not involve the ligands.
我们分析了胶体 CdSe 量子点 (QD) 悬浮液在通过配体稀释和滴定过程中荧光的衰减。由三辛基膦 (TOP)、油胺 (OA) 和硬脂酸 (SA) 组成的配体壳稳定了合成的 QD。使用高分辨率液相 1H 核磁共振 (NMR) 光谱分析并量化了壳的组成。通过稀释 QD 的储备溶液去除配体，观察到 QD 的荧光猝灭。通过添加 TOP 恢复荧光。我们通过假设 QD 之间猝灭剂的二项式分布来分析结果，并预测时间分辨荧光衰减的线性趋势。我们使用非参数分析表明，对于我们的 QD，通过去除 TOP，平均每个 QD 显示出 3.0 ± 0.1 个猝灭位。此外，我们表明猝灭位的猝灭速率相加。每个猝灭位的衰减可以与稀释效应饱和时的衰减进行比较。这为每个 QD 的猝灭剂数量提供了 2.88 ± 0.02 的值。我们提取了一个位点的猝灭动力学。它似乎是一个涉及速率分布的过程，不涉及配体。
