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Article Dans Une Revue Journal of Chemical Physics Année : 2004

Dissociative multiphoton ionization of NO2 studied by time-resolved imaging

Résumé

We have studied dissociative multiphoton ionization of NO2 by time-resolved velocity map imaging in a two-color pump-probe experiment using the 400 and 266 nm harmonics of a regeneratively amplified titanium-sapphire laser. We observe that most of the ion signal appears as NO+ with ~0.28 eV peak kinetic energy. Approximately 600 fs period oscillations indicative of wave packet motion are also observed in the NO+ decay. We attribute the signal to two competitive mechanisms. The first involving three-photon 400 nm absorption followed by dissociative ionization of the pumped state by a subsequent 266 nm photon. The second involving one-photon 400 nm absorption to the 2B2 state of NO2 followed by two-photon dissociative ionization at 266 nm. This interpretation is derived from the observation that the total NO+ ion signal exhibits biexponential decay, 0.72 exp(–t/90±10) + 0.28 exp(–t/4000±400), where t is the 266 nm delay in femtoseconds. The fast decay of the majority of the NO+ signal suggests a direct dissociation via the bending mode of the pumped state.

Dates et versions

hal-00084734 , version 1 (10-07-2006)

Identifiants

Citer

A. Eppink, B.J. Whitaker, Eric Gloaguen, B. Soep, M. Coroiu, et al.. Dissociative multiphoton ionization of NO2 studied by time-resolved imaging. Journal of Chemical Physics, 2004, 121, pp.7776-7783. ⟨10.1063/1.1795654⟩. ⟨hal-00084734⟩
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