Accession Number:

ADA270084

Title:

Photodissociation Studies of Polyatomic Free Radicals

Descriptive Note:

Final rept. 1 Jun 1989-30 Sep 1992

Corporate Author:

PUERTO RICO UNIV RIO PIEDRAS DEPT OF CHEMISTRY

Personal Author(s):

Report Date:

1993-08-01

Pagination or Media Count:

147.0

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 CH32SO, 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 photolysislaser 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 -0.70xlO exp-11 exp80.7 - 23.4KTcu cmmolecules. 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.

Subject Categories:

  • Physical Chemistry
  • Radiation and Nuclear Chemistry
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE