Dissociative multiphoton ionization of NO2 studied by time-resolved imaging

Eppink, André T. J. B.; Whitaker, Benjamin J.; Gloaguen, Éric; Soep, B.; Coroiu, A.M.; Parker, David H.

doi:10.1063/1.1795654

Cited by 32 publications

(98 citation statements)

References 49 publications

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“…The NO + and photoelectron images basically consist of a central spot, indicating that the transient responsible of the oscillations is produced with almost no kinetic energy. These oscillations are similar to those previously recorded in experiments for which the pump and probe pulse were 400 nm and 266 nm, respectively [26,27]. In that case, oscillation periods of 600 fs and 830 fs and a much shorter damping time of about 3 ps were obtained from the time dependence of the zero kinetic energy photoelectrons and NO + transients.…”

Section: Resultssupporting

confidence: 87%

Imaging fast relaxation dynamics of NO₂

et al. 2009

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Time-resolved spectroscopy combined with velocity map imaging technique have been used to investigate the multiphoton dynamics of NO 2 molecule. Two different pump-probe excitation schemes were used to explore different potential energy surfaces (PESs) located in the first dissociation region and in the Rydberg region around 9.2 eV. Integrated and energy resolved signals of NO + 2 , NO + and photoelectrons were recorded as a function of time. When exciting with 403 nm photons, the NO + signal exhibits an intriguing oscillatory behaviour with a period of 512 fs. The NO + and photoelectron kinetic energy distributions produced by this pump wavelength were cold, while those produced when employing 269 nm photons as pump were very rich, evidencing the presence of multiple excitation channels. A couple of sharp long lived photoion-photoelectron peaks represents the most salient feature of latter. They were assigned to an excitation by two 269 nm photons to a Rydberg state dissociating into NO(A 2 Σ + )+O( 3 P ). This NO + peak as well as another one located at 0 eV display very complex time dependencies including the signatures of two dissociation dynamics on timescales of 400 and 600 fs. The different pathways responsible of this temporal behaviour are discussed in view of shedding light onto the underlying multichannel multiphoton dynamics.

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Section: Resultssupporting

confidence: 87%

Imaging fast relaxation dynamics of NO₂

et al. 2009

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“…Only for the NO + fragment an enhancement is clearly observed at positive delay times, where the 400.4 nm photon is the pump and the 266.9 nm photon is the probe laser. In the pumpprobe experiments of Eppink et al 7 and Form et al, 8 an oscillatory NO + transient was observed at positive delay time. Such a oscillatory pattern is not very distinctly observed in our present data although the small increases in our NO + transients at 1000 and 1500 fs are reproducible.…”

Section: A Pump-probe Transientsmentioning

confidence: 90%

“…The effect of this conical intersection has been extensively studied in the frequency 5,6 and more recently also the time domain. [7][8][9][10] Depending on the typical time scale of the dissociation dynamics, femtosecond pump-probe laser spectroscopy can be used. However, the high field strength of femtosecond pulses easily induce multiphoton transitions in molecules and in general different competing photon pathways will contribute to the observed dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond time-resolved photoelectron-photoion coincidence imaging of multiphoton multichannel photodynamics in NO2

Vredenborg¹,

Roeterdink²,

Janssen³

2008

The Journal of Chemical Physics

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The multiphoton multichannel photodynamics of NO 2 has been studied using femtosecond time-resolved coincidence imaging. A novel photoelectron-photoion coincidence imaging machine was developed at the laboratory in Amsterdam employing velocity map imaging and "slow" charged particle extraction using additional electron and ion optics. The NO 2 photodynamics was studied using a two color pump-probe scheme with femtosecond pulses at 400 and 266 nm. The multiphoton excitation produces both NO 2 + parent ions and NO + fragment ions. Here we mainly present the time dependent photoelectron images in coincidence with NO 2 + or NO + and the ͑NO + , e͒ photoelectron versus fragment ion kinetic energy correlations. The coincidence photoelectron spectra and the correlated energy distributions make it possible to assign the different dissociation pathways involved. Nonadiabatic dynamics between the ground state and the A 2 B 2 state after absorption of a 400 nm photon is reflected in the transient photoelectron spectrum of the NO 2 + parent ion. Furthermore, Rydberg states are believed to be used as "stepping" states responsible for the rather narrow and well-separated photoelectron spectra in the NO 2 + parent ion. Slow statistical and fast direct fragmentation of NO 2 + after prompt photoelectron ejection is observed leading to formation of NO + + O. Fragmentation from both the ground state and the electronically excited a 3 B 2 and b 3 A 2 states of NO 2 + is observed. At short pump probe delay times, the dominant multiphoton pathway for NO + formation is a 3 ϫ 400 nm+ 1 ϫ 266 nm excitation. At long delay times ͑Ͼ500 fs͒ two multiphoton pathways are observed. The dominant pathway is a 1 ϫ 400 nm+ 2 ϫ 266 nm photon excitation giving rise to very slow electrons and ions. A second pathway is a 3 ϫ 400 nm photon absorption to NO 2 Rydberg states followed by dissociation toward neutral electronically and vibrationally excited NO͑A 2 ⌺ , v =1͒ fragments, ionized by one 266 nm photon absorption. As is shown in the present study, even though the pump-probe transients are rather featureless the photoelectron-photoion coincidence images show a complex time varying dynamics in NO 2 . We present the potential of our novel coincidence imaging machine to unravel in unprecedented detail the various competing pathways in femtosecond time-resolved multichannel multiphoton dynamics of molecules.

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“…[16][17][18][19][20][21][22] For C 2v geometries the two surfaces ͑ 2 A 1 and 2 B 2 ͒ intersect at a bond angle that depends on the bond length and form a one-dimensional CI seam. 17 The seam is located close to the bottom of the excited state and is readily accessible by a vibrational wavepacket launched onto the excited electronic surface from the Franck-Condon region of the ground state.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved photoelectron spectroscopy of wavepackets through a conical intersection in NO2

Arasaki

Takatsuka²,

Wang³

et al. 2010

The Journal of Chemical Physics

107

111

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We report the results of theoretical studies of the time-resolved femtosecond photoelectron spectroscopy of quantum wavepackets through the conical intersection between the first two 2 AЈ states of NO 2 . The Hamiltonian explicitly includes the pump-pulse interaction, the nonadiabatic coupling due to the conical intersection between the neutral states, and the probe interaction between the neutral states and discretized photoelectron continua. Geometry-and energy-dependent photoionization matrix elements are explicitly incorporated in these studies. Photoelectron angular distributions are seen to provide a clearer picture of the ionization channels and underlying wavepacket dynamics around the conical intersection than energy-resolved spectra. Time-resolved photoelectron velocity map images are also presented.

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Dissociative multiphoton ionization of NO2 studied by time-resolved imaging

Cited by 32 publications

References 49 publications

Imaging fast relaxation dynamics of NO₂

Imaging fast relaxation dynamics of NO₂

Femtosecond time-resolved photoelectron-photoion coincidence imaging of multiphoton multichannel photodynamics in NO2

Time-resolved photoelectron spectroscopy of wavepackets through a conical intersection in NO2

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Dissociative multiphoton ionization of NO2 studied by time-resolved imaging

Cited by 32 publications

References 49 publications

Imaging fast relaxation dynamics of NO2

Imaging fast relaxation dynamics of NO2

Femtosecond time-resolved photoelectron-photoion coincidence imaging of multiphoton multichannel photodynamics in NO2

Time-resolved photoelectron spectroscopy of wavepackets through a conical intersection in NO2

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Imaging fast relaxation dynamics of NO₂

Imaging fast relaxation dynamics of NO₂