TEMPERATURE-CONTROLLED MULTIPLE-PASS ABSORPTION CELL FOR GAS-PHASE CHEMICAL-KINETICS STUDIES

The application of a Herriott-type optical multiple pass cell for abso rption detection of transient species in temperature controlled laser pump-probe kinetics experiments is described. Using reaction initiatio n by laser photolysis in combination with reaction monitoring by absor ption of a multiple pass laser allows confinement of the probed reacti on volume to the temperature controlled region of a slow flow reactor. For transient measurements, this apparatus provides enhanced sensitiv ity from increased path length and accurate temperature control by lim iting the pump-probe interaction volume. In addition, for a polarized probe laser, a simple arrangement using a polarizing beam splitter and a lambda/4 plate allows doubling of the path length. (C) 1997 America n Institute of Physics.