HR: 0800h
AN: A51C-0778    [Abstracts]
TI: Evidence for O-Atom Exchange in the O($^1$D)~+~N$_2$O Reaction as the Source of Mass-Independent Isotopic Fractionation in Atmospheric N$_2$O
AU: * Liang, M
EM: mcl@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd. Caltech 150-21, Pasadena, CA 91125 United States
AU: Yung, Y L
EM: yly@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd. Caltech 150-21, Pasadena, CA 91125 United States
AU: Blake, G A
EM: gab@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd. Caltech 150-21, Pasadena, CA 91125 United States
AU: Muller, R P
EM: rmuller@sandia.gov
AF: Sandia National Laboratories, P.O. Box 5800, MS0196, Albuquerque, NM 87185 United States
AU: Miller, C E
EM: charles.e.miller@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Jet Propulsion Laboratory, Pasadena, CA 91109 United States
AB: Recent experiments have shown that in the oxygen isotopic exchange reaction for O($^1$D)~+~CO$_2$ the elastic channel is approximately 50% that of the inelastic channel [{\it Perri et al.,} 2003]. We propose an analogous oxygen atom exchange reaction for the isoelectronic O($^1$D)~+~N$_2$O system to explain the mass-independent isotopic fractionation (MIF) in atmospheric N$_2$O. We apply quantum chemical methods to compute the energetics of the potential energy surfaces on which the O($^1$D)~+~N$_2$O reaction occurs. Preliminary modeling results indicate that oxygen isotopic exchange via O($^1$D)~+~N$_2$O can account for the MIF oxygen anomaly if the oxygen atom isotopic exchange rate is 30-50% that of the total rate for the reactive channels.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting