Abstract
Rapid gas-phase chain reactions of Cl/sub 2//hydrocarbon mixtures are initiated by selective laser photodissociation of Cl/sub 2/ and investigated by time-resolved infrared emission spectra of chain products. The basic two-center chain chlorination reaction sequence is Cl. + RH ..-->.. HCl(nu) + R., R. + Cl/sub 2/ ..-->.. RCl/sup + +/ + Cl. (rate constants k/sub 1/ and k/sub 2/ apply to the reaction sequence). At low hydrocarbon reagent pressures ((RH) less than or equal to 20 Pa), analysis of emission from HCl(nu) is used to determine the chain rate constants k/sub 1/ and k/sub 2/ under controlled room temperature conditions. At higher pressures of RH (greater than or equal to 300 Pa) the chain reaction generates vibrationally excited polyatomic products, RCl/sup + +/, at rates comparable to or faster than relaxation of RCl/sup + +/. Time- and wavelength-resolved emission from vibrationally hot RCl/sup + +/ is used to investigate chain reaction behavior in this regime of rapidly rising temperatures. Extensive vibrational emission from reagent molecules is also observed, indicating a rapid and complete sharing of product vibrational excitation with the reagent molecules. The dispersed emission spectra of the products (3.0 to 15.0 ..mu..m) is fit by a simple model thatmore » assumes a common vibrational temperature, T/sub vib/, and varies the relative concentrations of the emitters. Product isomer ratios obtained from these spectral fits are in good agreement with literature values. Vibrational temperatures as high as 700/sup 0/K are observed. These are significantly hotter than the measured bulk gas temperatures (400 to 500/sup 0/ K), which suggests that the vibrational and translational degrees of freedom are not in equilibrium under the rapid burning conditions in these systems.« less
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
