HIGH-PRESSURE FAST-FLOW TECHNIQUE FOR GAS-PHASE KINETICS STUDIES

A fast-flow technique suitable for measuring elementary rate constants over a wide range of pressures has been developed. The method operate s under turbulent flow conditions, in contrast to laminar flow which c haracterizes the conventional low pressure technique. Flow visualizati on, velocity profile measurements, and tracer pulse studies have been carried out in a flow tube reactor to investigate the dynamics of both laminar and turbulent flow for chemical kinetics purposes. Furthermor e, the wall collision frequency for the reactants has been determined: at the higher pressures it is greatly reduced in comparison with the frequency characteristic of the conventional low pressure laminar flow technique. Also, to test and validate the technique the bimolecular r ate constants for the reactions H + Cl2 and H + O3 have been measured at total pressures in the 3-300 torr range; at pressures below 5 torr, as well as above 50 torr in the turbulent flow regime the agreement w ith the recommended literature values is excellent.