Session D11: Focus Session: Promises and Challenges in Chemical Dynamics III
2:30 PM–5:18 PM, Monday, March 13, 2006
Baltimore Convention Center Room: 303
Sponsoring Unit:
DCP
Chair: Laurie Butler, University of Chicago
Abstract ID: BAPS.2006.MAR.D11.2
Abstract: D11.00002 : Photodissociation dynamics of ethyl ethynyl ether: A ketenyl radical precursor
3:06 PM–3:18 PM
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Abstract 
Authors:
Maria Krisch
Johanna Miller
Laurie Butler
(University of Chicago)
Hongmei Su
Richard Bersohn
(Columbia University)
Jinian Shu
(Lawrence Berkeley National Laboratory)
We investigate the photodissociation dynamics of ethyl ethynyl ether at 193.3 nm with crossed laser-molecular beam photofragment translational spectroscopy and laser-induced fluorescence. We establish ethyl ethynyl ether as the first clean precursor to the ketenyl radical, a key species in combustion reactions. One major bond fission channel was observed for the system, cleavage along the HCCO-C$_{2}$H$_{5}$ bond, leading to ground state C$_{2}$H$_{5}$ (ethyl) radicals and HCCO (ketenyl) radical products in two distinct electronic states. We observed neither cleavage of the other C-O bond nor molecular elimination to form C$_{2}$H$_{4}$ + CH$_{2}$CO (ketene). Ketenyl radicals formed in the higher recoil kinetic energy channel could be either $\tilde {X}(^{2}$A") or \~{A}($^{2}$A') state ketenyl radical. We assign the lower recoil kinetic energy channel to the spin forbidden \~{a}($^{4}$A") state of the ketenyl radical, reached through intersystem crossing. Laser-induced fluorescence from the ketenyl radical peaks after a 20 $\mu $s delay, indicating that it is formed with a significant amount of internal energy and subsequently relaxes to the lowest vibrational level of the ground electronic state, a result consistent with the product assignment.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.D11.2