New laser induced photoacoustic signal measurement method. Example of application: Identification of the uranium(IV)-dioxalato complex in solution

Abstract

Summary A new laser induced photoacoustic signal measurement method was developed to optimise the parameters of photoacoustic detection: to obtain synchronous measurement, to avoid laser energy fluctuation, to get reproductibility and repeatability. The aim is to apply the technique to solution chemistry, and particularly to studies of the actinides. The initial validation of the new method was done using neodymium(III) and uranium(IV) solutions in acidic media. It was found that the sensitivity of detection of these ions by photoacoustic measurements is improved in comparison with absorption spectrophotometry. This advantage in radiochemistry is the possibility to study actinides at low concentration (<10-4M) to understand their behaviour in solution: speciation, precipitation, kinetics. An example is described and concerns the identification of the uranium(IV)-dioxalato complex in solution by proposing a new mechanism for the precipitation of U(C2O4)2·6H2O.In this work, a measurement device is proposed for rough pressure wave acquisition. It allows sensor definition, local phenomena observation and alternative LIPAS measurement.