Figure 1. On line monitoring of ZnO nanostructures reaction kinetics with different equimolar concentrations of the reagents (zinc nitrate and HMTA).

(a) Photograph of the quartz crystal microbalance and the adjacent Pt100 resistive temperature sensor, both supported by a Teflon bar; the temperature sensor is covered by an inert high-temperature silicone paste. (b) Reaction kinetics, at 90°C, quantified by the variation, for different growth times (time-step equal to one-hour), of the resonant frequency at different concentrations. (c) and (d) Resonant frequencies of the quartz-substrates versus time during the nanorods growth, at 90°C, for different equimolar concentrations of HMTA and zinc nitrate, ranging from 0.5 mM to 2.5 mM (c) and from 2.5 mM to 5 mM (d).