Microfluidic Channel Flow Cell for Simultaneous Cryoelectrochemical Electron Spin Resonance

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• 作者：Andrew J. Wain ; Richard G. Compton ; Rudolph Le Roux ; Sinead Matthews ; Adrian C. Fisher
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：March 1, 2007
• 年：2007
• 卷：79
• 期：5
• 页码：1865 - 1873
• 全文大小：232K
• 年卷期：v.79,no.5(March 1, 2007)
• ISSN：1520-6882

文摘

A novel microfluidic electrochemical channel flow cell hasbeen constructed for in situ operation in a cylindricalTE₀₁₁ resonant ESR cavity under variable temperatureconditions. The cell has a U-tube configuration, consistingof an inlet and outlet channel which run parallel andcontain evaporated gold film working, pseudo-reference,and counter electrodes. This geometry was employed topermit use in conjunction with variable temperatureapparatus which does not allow a flow-through approach.The cell is characterized qualitatively and quantitativelyusing the one-electron reduction of p-bromonitrobenzenein acetonitrile at room temperature as a model system,and the ESR signal-flow rate response is validated by useof three-dimensional digital simulation of the concentration profile for a stable electrogenerated radical speciesunder hydrodynamic conditions. The cell is then used toobtain ESR spectra for a number of radical species inacetonitrile at 233 K, including the radical anions of m-and p-iodonitrobenzene, o-bromonitrobenzene, and m-nitrobenzyl chloride, the latter three being unstable atroom temperature. Spectra are also presented for theradical anion of 2-chloranthraquinone and the crystalviolet radical, which display improved resolution at lowtemperatures.