Dissociative multiphoton ionization of NO{sub 2} studied by time-resolved imaging

Journal Article · Fri Oct 22 04:00:00 EDT 2004 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.1795654· OSTI ID:20662127

Whitaker, Benjamin J; Gloaguen, Eric; Soep, Benoit; Coroiu, A Marcela; Parker, David H ^[1]

---

1. School of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom)

We have studied dissociative multiphoton ionization of NO{sub 2} 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{sup +} with {approx}0.28 eV peak kinetic energy. Approximately 600 fs period oscillations indicative of wave packet motion are also observed in the NO{sup +} 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 {sup 2}B{sub 2} state of NO{sub 2} followed by two-photon dissociative ionization at 266 nm. This interpretation is derived from the observation that the total NO{sup +} 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{sup +} signal suggests a direct dissociation via the bending mode of the pumped state.

• OSTI ID: 20662127
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 16 Vol. 121; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
DECAY
HARMONICS
KINETIC ENERGY
LASERS
MILLI EV RANGE
MULTI-PHOTON PROCESSES
NITROGEN DIOXIDE
PHOTOIONIZATION
PHOTON-MOLECULE COLLISIONS
PHOTONS
SPECTRA
TIME RESOLUTION
WAVE PACKETS