Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation
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Issue Date
2007-04-25Author
Elles, Christopher G.
Shkrob, Ilya A.
Crowell, Robert A.
Bradforth, Stephen E.
Publisher
American Institute of Physics
Type
Article
Article Version
Scholarly/refereed, publisher version
Metadata
Show full item recordAbstract
The authors use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The primary decay mechanism changes from dissociation at an excitation energy of 8.3eV to ionization at 12.4eV. The two channels occur with similar yield for an excitation energy of 9.3eV. For the lowest excitation energy, the transient absorption at 267nm probes the geminate recombination kinetics of the H and OH fragments, providing a window on the dissociation dynamics. Modeling the OH geminate recombination indicates that the dissociating H atoms have enough kinetic energy to escape the solvent cage and one or two additional solvent shells. The average initial separation of H and OH fragments is 0.7±0.2nm. Our observation suggests that the hydrogen bonding environment does not prevent direct dissociation of an O–H bond in the excited state. We discuss the implications of our measurement for the excited state dynamics of liquid water and explore the role of those dynamics in the ionization mechanism at low excitation energies.
Description
This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/126/16/10.1063/1.2727468.
ISSN
0021-9606Collections
Citation
Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Bradforth, Stephen E. (2007). "Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation." The Journal of Chemical Physics, 126:164503. http://dx.doi.org/10.1063/1.2727468.
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