The stopped-drop method: a novel setup for containment-free and time-resolved measurements

A novel setup for containment‐free time‐resolved experiments at a free‐hanging drop is reported. Within a dead‐time of 100 ms a drop of mixed reactant solutions is formed and the time evolution of a reaction can be followed from thereon by various techniques. As an example, a small‐angle X‐ray scattering study on the formation mechanism of EDTA‐stabilized CdS both at a synchrotron and a laboratory X‐ray source is presented here. While the evolution can be followed with one drop only at a synchrotron source, a stroboscopic mode with many drops is preferable for the laboratory source. Free‐hanging drops from homogeneously mixed solutions allow containment‐free time‐resolved measurements with an initial dead‐time of 100 ms. This has been used to explore the formation mechanism of EDTA‐stabilized CdS quantum dots, both at a synchrotron source in a single‐shot mode and at a laboratory source in a stroboscopic mode.