Instrumentation of kinetic spectroscopy—7. A precision integrator for measuring the excitation in laser flash photolysis and pulse radiolysis experiments

Abstract

An electronic circuit is described which integrates current against time with high resolution and precision. By connecting a suitable detector (a photodiode in laser flash photolysis experiments, or, either a secondary emission chamber or a current pick-up in pulse radiolysis experiments) to this circuit, the excitation can be measured. This integrator is suitable for the measurement of excitation over a wide range and is especially useful for monitoring extremely low values. The resulting is about 3E-12 As, which corresponds to initial radical concentrations of less than 1 nM in pulse radiolysis experiments.