In situ observation of UF5 nanoparticle growth in a low-pressure mixed-flow reactor

A mixed-flow reactor for the generation of UF5 nanoparticles equipped with an in situ size-monitoring system, a LPDMA (low-pressure differential mobility analyzer), was developed to experimentally investigate the nanoparticle growth mechanism. The concentration of photoproduced UF5 molecules was controlled by changing three factors: (I) the concentration of the feed UF6 gas, (II) the laser pulse energy of the irradiation, and (III) the repetition rate of the laser pulses. The dependence of the volumetric average diameter of the photoproduced particles on the UF5 nascent concentration in all three cases was found to be very similar. The result strongly suggests that the reactor functions as a mixed-flow reactor under a complete mixing condition. The particle size measured by the LPDMA was found to be in the range of 6 to 11 nm. and it was approximately proportional to the power 0.3 of the initial concentration of photoproduced UF5 molecules.