We report a new mass spectrometric method for detecting electrogenerated intermediates. This approach is based on simultaneous activation of electrospray ionization and redox reaction on a wireless bipolar ultramicroelectrode, which is fabricated in the tip of a quartz nanopipette. The hollow structure of the ultramicroelectrode permits rapid transferring the transient species from electrode–electrolyte interfaces into the gas phase for mass spectrometric identification on the time scale of microseconds. The long‐sought fleeting intermediates including TPrA^.+, whose lifetime in solution is only 200 μs, and catecholamine o‐semiquinone radicals, the second‐order rate constant of which is typically 10⁹ m⁻¹ s⁻¹, were successfully identified, helping clarify the previously hidden reaction pathways. Accordingly, our method may have wide applicability in exploring the dynamics of many electrochemical reactions, especially their ultrafast initial steps.

中文翻译：

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无线双极超微电极与纳米电喷雾电离质谱的耦合：深入了解电化学反应的超快初始步骤。

我们报告了一种检测电生成中间体的新质谱方法。该方法基于在石英纳米移液器尖端制造的无线双极超微电极上同时激活电喷雾电离和氧化还原反应。超微电极的中空结构可以将瞬态物质从电极-电解质界面快速转移到气相中，以便在微秒的时间范围内进行质谱鉴定。长期寻求的短暂中间体，包括TPrA ^。+（其在溶液中的寿命仅为200μs）和儿茶酚胺邻半醌自由基，其二级速率常数通常为10 ⁹  m ^-1  s ^-1被成功鉴定，有助于弄清以前隐藏的反应途径。因此，我们的方法在探索许多电化学反应的动力学，特别是其超快的初始步骤中可能具有广泛的适用性。