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Makhija V, Boguslavskiy AE, Forbes R, Veyrinas K, Wilkinson I, Lausten R, Schuurman MS, Grant ER, Stolow A. A quantum molecular movie: polyad predissociation dynamics in the VUV excited 3pσ 2Σ u state of NO 2. Faraday Discuss 2021; 228:191-225. [PMID: 33629690 DOI: 10.1039/d0fd00128g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The optical formation of coherent superposition states, a wavepacket, can allow the study of zeroth-order states, the evolution of which exhibit structural and electronic changes as a function of time: this leads to the notion of a molecular movie. Intramolecular vibrational energy redistribution, due to anharmonic coupling between modes, is the molecular movie considered here. There is no guarantee, however, that the formed superposition will behave semi-classically (e.g. Gaussian wavepacket dynamics) or even as an intuitively useful zeroth-order state. Here we present time-resolved photoelectron spectroscopy (TRPES) studies of an electronically excited triatomic molecule wherein the vibrational dynamics must be treated quantum mechanically and the simple picture of population flow between coupled normal modes fails. Specifically, we report on vibronic wavepacket dynamics in the zeroth-order 3pσ2Σu Rydberg state of NO2. This wavepacket exemplifies two general features of excited state dynamics in polyatomic molecules: anharmonic multimodal vibrational coupling (forming polyads); nonadiabatic coupling between nuclear and electronic coordinates, leading to predissociation. The latter suggests that the polyad vibrational states in the zeroth-order 3p Rydberg manifold are quasi-bound and best understood to be scattering resonances. We observed a rapid dephasing of an initially prepared 'bright' valence state into the relatively long-lived 3p Rydberg state whose multimodal vibrational dynamics and decay we monitor as a function of time. Our quantum simulations, based on an effective spectroscopic Hamiltonian, describe the essential features of the multimodal Fermi resonance-driven vibrational dynamics in the 3p state. We also present evidence of polyad-specificity in the state-dependent predissociation rates, leading to free atomic and molecular fragments. We emphasize that a quantum molecular movie is required to visualize wavepacket dynamics in the 3pσ2Σu Rydberg state of NO2.
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Affiliation(s)
- Varun Makhija
- Department of Chemistry and Physics, University of Mary Washington, Fredericksburg, VA 22401, USA and Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada.
| | - Andrey E Boguslavskiy
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada. and National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1N 5A2, Canada
| | - Ruaridh Forbes
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada. and SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, California 94025, USA
| | - Kevin Veyrinas
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada.
| | - Iain Wilkinson
- Locally-Sensitive & Time-Resolved Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Rune Lausten
- National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1N 5A2, Canada
| | - Michael S Schuurman
- National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1N 5A2, Canada and Department of Chemistry, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada
| | - Edward R Grant
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Albert Stolow
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada. and National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1N 5A2, Canada and Department of Chemistry, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada
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Elkharrat C, Picard YJ, Billaud P, Cornaggia C, Garzella D, Perdrix M, Houver JC, Lucchese RR, Dowek D. Ion Pair Formation in Multiphoton Excitation of NO2 Using Linearly and Circularly Polarized Femtosecond Light Pulses: Kinetic Energy Distribution and Fragment Recoil Anisotropy. J Phys Chem A 2010; 114:9902-18. [DOI: 10.1021/jp103672h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. Elkharrat
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - Y. J. Picard
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - P. Billaud
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - C. Cornaggia
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - D. Garzella
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - M. Perdrix
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - J. C. Houver
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - R. R. Lucchese
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
| | - D. Dowek
- Institut des Sciences Moléculaires d’Orsay, UMR8214 Univ Paris-Sud et CNRS, Bat. 350, F-91405 Orsay Cedex, France, Service Photons Atomes & Molécules, CEA IRAMIS, Service des Photons, Atomes et Molécules, Saclay, Bat. 522, F-91191 Gif-sur-Yvette, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
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Irimia D, Petsalakis ID, Theodorakopoulos G, Janssen MHM. Coherent oscillatory femtosecond dynamics in multichannel photodynamics of NO2 studied by spatially masked electron imaging. J Phys Chem A 2010; 114:3157-66. [PMID: 19928822 DOI: 10.1021/jp909031p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The femtosecond multiphoton photoionization and dissociation dynamics of NO(2) have been studied in a two-color pump-probe experiment at 400 and 266 nm using velocity map ion imaging in conjunction with photoelectron imaging. We report here a series of experiments focusing on the oscillatory patterns in pump-probe transients of the photoelectron signal. By using the technique of spatially masked imaging detection, we can select different photoelectron channels enabling the rapid measurement of energy selected transients with good signal-to-noise ratio. At short delay times (<300 fs) the dominant process is dissociative multiphoton ionization by 3 x 400 nm + 1 x 266 nm excitation to a repulsive potential energy surface of the NO(2)(+) cation correlating to NO(+)((1)Sigma(+)) + O((3) P) and the ejection of a 0.37 eV electron. At longer delay times (>400 fs), the release of high-energy electrons (0.88 eV) is observed attributed to a three-photon absorption at 400 nm to Rydberg and valence type excited states of neutral NO(2) leading to predissociation and the production of NO(+) + O((3)P) from a one-photon ionization at 266 nm. At longer delay times (>400 fs) a second slow (near 0 eV) photoelectron channel is observed that is associated with one photon excitation at 400 nm to the first excited A(2)B(2) state of NO(2) followed by two-photon excitation at 266 nm leading to near threshold ionization and dissociation to NO(+) + O((3)P). Distinctive oscillatory patterns were found in the pump-probe transients of the photoelectron yield for both the slow and the fast photoelectron channels but with different periods of about 750 fs (slow) or 590 fs (fast). Extensive polarization experiments are reported for both linear and circular polarized pump and probe laser geometries. We discuss the oscillatory mechanism in relation to ab initio calculations of relevant Rydberg and valence type excited states of NO(2) near 9.3 eV. We propose that an oscillating wavepacket of mixed Rydberg and valence character that predissociates is responsible for the observed oscillations in the transients of the fast (0.88 eV) photoelectron channel.
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Affiliation(s)
- Daniel Irimia
- Laser Centre and Department of Chemistry, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Vredenborg A, Roeterdink WG, Janssen MHM. Femtosecond time-resolved photoelectron-photoion coincidence imaging of multiphoton multichannel photodynamics in NO2. J Chem Phys 2008; 128:204311. [PMID: 18513023 DOI: 10.1063/1.2924134] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
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(+),e) 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 3x400 nm+1x266 nm excitation. At long delay times (>500 fs) two multiphoton pathways are observed. The dominant pathway is a 1x400 nm+2x266 nm photon excitation giving rise to very slow electrons and ions. A second pathway is a 3x400 nm photon absorption to NO(2) Rydberg states followed by dissociation toward neutral electronically and vibrationally excited NO(A (2)Sigma,v=1) 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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Affiliation(s)
- Arno Vredenborg
- Laser Centre and Department of Chemistry, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Form NT, Whitaker BJ, Poisson L, Soep B. Time-resolved photoion and photoelectron imaging of NO2. Phys Chem Chem Phys 2006; 8:2925-32. [PMID: 16880904 DOI: 10.1039/b602825j] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoion and photoelectron velocity mapped images from NO(2) excited close to its first dissociation limit [to NO(X(2)Pi) + O((3)P(2))] have been recorded in a two colour pump-probe experiment, using the frequency-doubled and frequency-tripled output of a regeneratively amplified titanium-sapphire laser. At least three processes are responsible for the observed transient signals; a negative pump-probe signal (corresponding to a 266 nm pump), a very short-lived transient close to the cross-correlation of the pump and probe pulses but on the 400 nm pump side, and a longer-lived positive pump-probe signal that exhibits a signature of wavepacket motion (oscillations). These transients have two main origins; multiphoton excitation of the Rydberg states of NO(2) by both 266 and 400 nm light, and electronic relaxation in the 1(2)B(2) state of NO(2), which leads to a quasi-dissociated NO(2) high in the 1(2)A(1) electronic ground state and just below the dissociation threshold. The wavepacket motion that we observe is ascribed to states exhibiting free rotation of the O atom about the NO moiety. These states, which are common for loosely bound systems such as a van der Waals complex but unusual for a chemically-bound molecule, have previously been observed in the frequency domain by optical double resonance spectroscopy but never before in the time domain.
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