title: Pulsed-accelerated-flow spectrometer with position-resolved observation.
abstract: The title instrument (PAF-PRO) permits the progress of rapid reactions to be monitored at 128 positions along a 2 cm observation cell as reactants flow down the cell. A decelerated push is used to give velocity changes from 21 to 2 m s(-1) during a time interval of 384 ms. Variation of flow velocity allows reaction rate constants to be resolved from the physical mixing process. The flow system brings the reacting solutions together in a 10-jet radial mixer 0.32 cm before the mixture enters the observation tube (0.203 cm width, 1.945 cm length). A masked charge-coupled device (CCD) is the array detector used to obtain transmittance data as a function of position and velocity. The masked portion of the CCD serves as a dynamic memory buffer for fast data acquisition. Pseudo-first-order rate constants are measured from 200 to 12 000 s(-1). The instrument also is calibrated for second-order reactions (equal concentrations) with initial half-lives of 0.3-1.5 ms. Applications of the PAF-PRO system for the study of fast multistep reactions are presented.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
authors.forename: M R
authors.initials: MR
authors.lastname: McDonald
authors.forename: T X
authors.initials: TX
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Gazda
authors.forename: W M
authors.initials: WM
authors.lastname: Scheper
authors.forename: S W
authors.initials: SW
authors.lastname: Evetts
authors.forename: D W
authors.initials: DW
authors.lastname: Margerum