Halide (Cl-) quenching of quinine sulfate fluorescence: A time-resolved fluorescence experiment for physical chemistry
Halide (Cl-) quenching of quinine sulfate fluorescence: A time-resolved fluorescence experiment for physical chemistry
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DOI：
10.1021/ed082p302
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发表时间：
2005-02-01
影响因子：
3
通讯作者：
Gutow, JH
中科院分区：
文献类型：
--
作者：
Gutow, JH
本文介绍了一个用于物理化学的时间分辨荧光实验。学生研究卤化物对硫酸奎宁在水中（类似于奎宁水）发出的荧光的猝灭。学生们能够确定荧光是通过与卤化物碰撞而动态猝灭的，而不是通过形成平衡的复合物。学生们重现了文献中约19 ns的未淬灭寿命，并观察到0.5 M H2SO 4中5.2 × 109 M-1的近扩散限制碰撞淬灭速率。这个实验很受学生欢迎。样品易于处理。它为学生提供了现代设备（激光，快速数据收集和计算机数据分析）的经验，同时也要求学生审查和使用竞争过程和电子光谱学的动力学知识。不同浓度的样品被分配给学生进行分析;以这种方式，9名学生可以在一个三小时的实验室中使用单个荧光仪器完成实验的数据收集。如果时间分辨率不可用，这个实验仍然可以使用强度测量来进行。猝灭产生线性Stern-Volmer图，aKsv为107 M-1。
A time-resolved fluorescence experiment for use in physical chemistry is described. Students investigate the halide quenching of the fluorescence from quinine sulfate in water (similar to tonic water). The students are able to determine that the fluorescence is quenched dynamically by collision with the halide, not by forming an equilibrated complex. Students reproduce the literature unquenched lifetime of about 19 ns and observe a nearly diffusion-limited collisional quenching rate of 5.2 × 109 M–1in 0.5 M H2SO4. The experiment is popular with the students. The samples are easy to handle. It provides the students experience with modern equipment (lasers, fast data collection, and computer data analysis), while also requiring the students to review and use knowledge of the kinetics of competing processes and electronic spectroscopy. Samples of different concentration are divided among the students for analysis; in this manner nine students can complete the data collection for the experiment in one three-hour laboratory using a single fluorescence apparatus. If time resolution is not available this experiment can still be performed using intensity measurements. The quenching yields linear Stern–Volmer plots with aKsv≈107 M–1.