| First, a system including 4 independently controlled syringes and 3 mixers (SFM-400 stopped flow, figure 1) that allows rapid mixing of 2 or 3 liquid reactants to study the chemical kinetics of a reaction in solution. With this device, the dead time (i.e. time between the end of mixing of solutions and the beginning of observation of the kinetics of the reaction) is reduced down to 0.25 ms, which is ideal to study the dynamics of homogenous catalytic reactions and nucleation of metal nano-particles. The second setup is a detector (fast silicon detector quantum ULTRA Data Acquisition-DAQ) that allows XANES/EXAFS measurements on dynamics of homogenous catalytic reaction in diluted solution with microsecond (µs) resolution. Furthermore, the standard configuration of the stopped-flow device facilitates versatile probe methods: with EXAFS but also various optical modes: absorbance, fluorescence, circular dichroism, and fluorescence anisotropy.
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Figure 1: SFM-400 stopped flow system
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The first experiments, carried out in December 2009, were EXAFS analysis on Fe(CO)5 in methanol 0.37 mM (figure 2). Various acquisition times were tested, and a time resolution of 10 µs was obtained for the diluted solution.
Figure 2-A) EXAFS measurement on Fe(CO)5 in methanol 0.37 mM with the silicon quantum detector (ULTRA Data Acquisition-DAQ), with various acquisition time. A time resolution of 10 µs can be obtained for the diluted solution. The sharp peaks come from a dead point of the detector.
2-B) Test solution of Fe(CO)5 in methanol with various concentrations: 0.18 mM, 0.37mM, and 0.78mM, in 1mm capillary.
These performances already attract chemists and researchers in environmental sciences, for whom such a time resolution is a unique tool for a better understanding of reaction mechanisms.
