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Direct mapping of recoil in the ion-pair dissociation of molecular oxygen by a femtosecond depletion method
- Source :
- Journal of Chemical Physics, Journal of Chemical Physics, 2008, 129, pp.214306. ⟨10.1063/1.3026613⟩, Journal of Chemical Physics, 129, 214306-214306-9, Journal of Chemical Physics, American Institute of Physics, 2008, 129, pp.214306. ⟨10.1063/1.3026613⟩, Journal of Chemical Physics, 129, 21, pp. 214306-214306-9
- Publication Year :
- 2008
-
Abstract
- Time-resolved dynamics of the photodissociation of molecular oxygen, O(2), via the (3)Sigma(u) (-) ion-pair state have been studied with femtosecond time resolution using a pump-probe scheme in combination with velocity map imaging of the resulting O(+) and O(-) ions. The fourth harmonic of a femtosecond titanium-sapphire (Ti:sapphire) laser (lambda approximately 205 nm) was found to cause three-photon pumping of O(2) to a level at 18.1 eV. The parallel character of the observed O(+) and O(-) images allowed us to conclude that dissociation takes place on the (3)Sigma(u) (-) ion-pair state. The 815 nm fundamental of the Ti:sapphire laser used as probe was found to cause two-photon electron photodetachment starting from the O(2) ion-pair state, giving rise to (O((3)P)+O(+)((4)S)) products. This was revealed by the observed depletion of the yield of the O(-) anion and the appearance of a new O(+) cation signal with a kinetic energy E(transl)(O(+)) dependent on the time delay between the pump and probe lasers. This time-delay dependence of the dissociation dynamics on the ion-pair state has also been simulated, and the experimental and simulated results coincide very well over the experimental delay-time interval from about 130 fs to 20 ps where two- or one-photon photodetachment takes place, corresponding to a change in the R(O(+),O(-)) interatomic distance from 12 to about 900 A. This is one of the first implementations of a depletion scheme in femtosecond pump-probe experiments which could prove to be quite versatile and applicable to many femtosecond time-scale experiments.
- Subjects :
- Time Factors
Analytical chemistry
General Physics and Astronomy
Color
Physics::Optics
Electron
010402 general chemistry
Kinetic energy
01 natural sciences
Dissociation (chemistry)
law.invention
Ion
Optical pumping
law
0103 physical sciences
Physics::Atomic and Molecular Clusters
Physical and Theoretical Chemistry
GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Photons
Photolysis
010304 chemical physics
Chemistry
Photodissociation
Laser
0104 chemical sciences
Oxygen
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry
Femtosecond
Molecular and Laser Physics
Atomic physics
Subjects
Details
- ISSN :
- 00219606 and 10897690
- Volume :
- 129
- Database :
- OpenAIRE
- Journal :
- Journal of Chemical Physics
- Accession number :
- edsair.doi.dedup.....5d1c65c569ce397ba627e2753534ecc6