Development of an in-situ monitoring tool for Actinide ions

假设：在水溶液中，锕系元素如U、Np和Pu作为离子在电磁波谱的紫外线、可见光和/或近红外区被强烈吸收。这表明，照明将通过促进电子来导致每个离子的光激发，该电子可能被共定位电极直接捕获（光物理-电化学机制），或通过使用有效延长光激发物质寿命的电子清除剂间接捕获（光物理-化学-电化学机制）。MORE的设计是围绕光纤光导构建的，这使得它能够将单色光传递到探测体，在那里，围绕光导的金环电极被理想地定位于电化学检测通常是短暂的光激发物质或其衰变或淬火的产物。(i)单色光和（ii）电极的工作电位所提供的微调能力，允许根据分析物的光物理和电化学性质来识别分析物。MORE已被证明能够检测溶液中少量（低至200 nmol - dm-3）的光电活性分析物。至关重要的是，发现光电流的振幅取决于照明的波长，并与分析物的吸收光谱密切匹配。因此，它可以用来询问光谱特性足够明显的混合物中分析物的单个浓度。该项目的主要目的是开发一种方法，以充分表征含有一系列目标分析物的水溶液，包括U， Pu和Np，使用微光学环电极。导师：法布里斯·安德烈博士

HypothesesIn aqueous solutions, actinides such as U, Np and Pu are encountered as ions which absorb intensely in the ultraviolet, visible and/or near infrared region of the electromagnetic spectrum. This indicates that illumination will result in the photoexcitation of each of those ions by promotion of an electron which may be captured by co-localised electrode either directly (photophysical-electrochemical mechanism) or indirectly via the use of an electron scavenger that effectively acts to extend the lifetime of the photoexcited species (photophysical-chemical-electrochemical mechanism). The MORE's design is built around an optical fibre light guide, which enables it to deliver monochromated light to the interrogation volume where the gold ring electrode surrounding the light guide is ideally located to electrochemically detect the often short-lived photoexcited species or the product of its decay or quenching. The fine-tuning capabilities afforded by (i) monochromated light and (ii) the electrode's working potential, allow to identify analytes based on their photophysical and electrochemical properties. The MORE has been shown capable of detecting small amounts (down to 200 nmol dm-3) of photo-electroactive analytes in solution. Crucially, it was found that the amplitude of the photocurrent is dependent on the wavelength of illumination and closely matches the absorption spectrum for the analyte. Thus, it can be used to interrogate the individual concentrations of analytes in mixtures whose spectroscopic properties are sufficiently distinct. Aims The main aim of this project is to develop a methodology to fully characterise aqueous solutions containing a range of target analytes including U, Pu and Np using the Micro-Optical Ring Electrode.Supervisor: Dr Fabrice Andrieux