Photodissociation Studies of Polyatomic Free Radicals
Abstract
An experimental program in gas phase polyatomic photochemistry and photophysics has been extablished in the Department of Chemistry at the University of Puerto Rico. Real time dynamics of sulfur monoxide photoelimination reactions have been studied by laser induced fluorescence spectroscopy of the nascent SO fragment on the B3 sigma (-) -X3 sigma (-) transition in the region of 237-295 nm. The group of molecules under investigation are Sulfur dioxide (SO2), dimethyl sulfoxide (CH3)2SO), and the thionyl halides (SOX2; where X = F,Cl or Br). In all of these experiments, the parent molecule is irradiated with an excimer laser (either 193 or 248 nm) and the energy disposal into the nascent SO photofragment is determined, and used as a mechanistic probe. The experiments indicate that the several of these parent molecules undergo three body dissociations. A second set of experiments measures kinetic decay constants of the C2H3O, both in the ground state and in the excited state. The temperature (295-374K) and pressure (2.5-100 torr) dependences for the rate constant of the C2H30 + N02 reaction have been measured by laser flash photolysis/laser induced fluorescence kinetic spectroscopy. The temperature dependent reaction for the decay of C2H3O in the presence of N02 is characterized over the measured region by the rate expression, k sub II = (1.48 +/-0.70)xlO( exp-11) exp(80.7 +/- 23.4K/T)cu cm/molecule/s. Fluorescence decay rates were determined in the presence to ten collision partners: He, Ar, N2, 02, CO, H2, HCl, C02, C2H4,, and CH30CH = CH2. The measured electronic quenching cross-sections vary from 0.01 - 66.5 A2. A vibrational level dependence was found for the radiative lifetimes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1993
- Accession Number
- ADA270084
Entities
People
- Brad R Weiner
Organizations
- University of Puerto Rico