Versatile Stopped Flow Temperature Jump Apparatus

A stopped flow temperature jump apparatus is described which permits rapid mixing of reactants and application of a temperature perturbation to the reacting system from 16 msec to several seconds or longer after mixing. The apparatus consists of a flow system with a rectangular observation chamber 1 cm in length. Electrodes are fixed above and below the observation chamber. A stopping syringe activates the time delay, switching, and triggering circuits. The triggering circuit discharges a high voltage capacitor through the solution in the observation chamber, producing a 5°K temperature jump in about 50 μsec. The response of the reacting system is monitored with absorption spectrophotometry.