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Larsen KA, Bello RY, Lucchese RR, McCurdy CW, Slaughter DS, Weber T. Strongly coupled intermediate electronic states in one-color two-photon single valence ionization of O 2. J Chem Phys 2023; 158:024303. [PMID: 36641397 DOI: 10.1063/5.0128846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We present an experimental and theoretical energy- and angle-resolved investigation on the non-dissociative photoionization dynamics of near-resonant, one-color, two-photon, single valence ionization of neutral O2 molecules. Using 9.3 eV femtosecond pulses produced via high harmonic generation and a 3-D momentum imaging spectrometer, we detect the photoelectrons and O2 + cations produced from one-color, two-photon ionization in coincidence. The measured and calculated photoelectron angular distributions show agreement, which indicates that a superposition of two intermediate electronic states is dominantly involved and that wavepacket motion on those near-resonantly populated intermediate states does not play a significant role in the measured two-photon ionization dynamics. Here, we find greater utility in the diabatic representation compared to the adiabatic representation, where invoking a single valence-character diabat is sufficient to describe the underlying two-photon ionization mechanism.
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Affiliation(s)
- Kirk A Larsen
- Graduate Group in Applied Science and Technology, University of California, Berkeley, California 94720, USA
| | - Roger Y Bello
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert R Lucchese
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C William McCurdy
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel S Slaughter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Thorsten Weber
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Larsen KA, Lucchese RR, Slaughter DS, Weber T. Distinguishing resonance symmetries with energy-resolved photoion angular distributions from ion-pair formation in O 2 following two-photon absorption of a 9.3 eV femtosecond pulse. J Chem Phys 2020; 153:021103. [PMID: 32668943 DOI: 10.1063/5.0013485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a combined experimental and theoretical study on the photodissociation dynamics of ion-pair formation in O2 following resonant two-photon absorption of a 9.3 eV femtosecond pulse, where the resulting O+ ions are detected using 3D momentum imaging. Ion-pair formation states of Σg-3 and 3Πg symmetry are accessed through predissociation of optically dark continuum Rydberg states converging to the B Σg-2 ionic state, which are resonantly populated via a mixture of both parallel-parallel and parallel-perpendicular two-photon transitions. This mixture is evident in the angular distribution of the dissociation relative to the light polarization and varies with the kinetic energy release (KER) of the fragmenting ion pair. The KER-dependent photoion angular distribution reveals the underlying two-photon absorption dynamics involved in the ion-pair production mechanism and indicates the existence of two nearly degenerate continuum resonances possessing different symmetries, which can decay by coupling to ion-pair states of the same total symmetry through internal conversion.
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Affiliation(s)
- Kirk A Larsen
- Graduate Group in Applied Science and Technology, University of California, Berkeley, California 94720, USA
| | - Robert R Lucchese
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel S Slaughter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Thorsten Weber
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Larsen KA, Cryan JP, Shivaram N, Champenois EG, Wright TW, Ray D, Kostko O, Ahmed M, Belkacem A, Slaughter DS. VUV and XUV reflectance of optically coated mirrors for selection of high harmonics. OPTICS EXPRESS 2016; 24:18209-18216. [PMID: 27505785 DOI: 10.1364/oe.24.018209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the reflectance, ~1° from normal incidence, of six different mirrors as a function of photon energy, using monochromatic vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) radiation with energies between 7.5 eV and 24.5 eV. The mirrors examined included both single and multilayer optical coatings, as well as an uncoated substrate. We discuss the performance of each mirror, paying particular attention to the potential application of suppression and selection of high-order harmonics of a Ti:sapphire laser.
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Sturm FP, Wright TW, Ray D, Zalyubovskaya I, Shivaram N, Slaughter DS, Ranitovic P, Belkacem A, Weber T. Time resolved 3D momentum imaging of ultrafast dynamics by coherent VUV-XUV radiation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:063110. [PMID: 27370429 DOI: 10.1063/1.4953441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/25/2016] [Indexed: 06/06/2023]
Abstract
We present a new experimental setup for measuring ultrafast nuclear and electron dynamics of molecules after photo-excitation and ionization. We combine a high flux femtosecond vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) source with an internally cold molecular beam and a 3D momentum imaging particle spectrometer to measure electrons and ions in coincidence. We describe a variety of tools developed to perform pump-probe studies in the VUV-XUV spectrum and to modify and characterize the photon beam. First benchmark experiments are presented to demonstrate the capabilities of the system.
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Affiliation(s)
- F P Sturm
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T W Wright
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D Ray
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - I Zalyubovskaya
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - N Shivaram
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D S Slaughter
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - P Ranitovic
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A Belkacem
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Th Weber
- Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Allison TK, Tao H, Glover WJ, Wright TW, Stooke AM, Khurmi C, van Tilborg J, Liu Y, Falcone RW, Martínez TJ, Belkacem A. Ultrafast internal conversion in ethylene. II. Mechanisms and pathways for quenching and hydrogen elimination. J Chem Phys 2012; 136:124317. [DOI: 10.1063/1.3697760] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Tao H, Allison TK, Wright TW, Stooke AM, Khurmi C, van Tilborg J, Liu Y, Falcone RW, Belkacem A, Martinez TJ. Ultrafast internal conversion in ethylene. I. The excited state lifetime. J Chem Phys 2011; 134:244306. [PMID: 21721629 DOI: 10.1063/1.3604007] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Using a combined theoretical and experimental approach, we investigate the non-adiabatic dynamics of the prototypical ethylene (C(2)H(4)) molecule upon π → π∗ excitation. In this first part of a two part series, we focus on the lifetime of the excited electronic state. The femtosecond time-resolved photoelectron spectrum (TRPES) of ethylene is simulated based on our recent molecular dynamics simulation using the ab initio multiple spawning method with multi-state second order perturbation theory [H. Tao, B. G. Levine, and T. J. Martinez, J. Phys. Chem. A 113, 13656 (2009)]. We find excellent agreement between the TRPES calculation and the photoion signal observed in a pump-probe experiment using femtosecond vacuum ultraviolet (hν = 7.7 eV) pulses for both pump and probe. These results explain the apparent discrepancy over the excited state lifetime between theory and experiment that has existed for ten years, with experiments [e.g., P. Farmanara, V. Stert, and W. Radloff, Chem. Phys. Lett. 288, 518 (1998) and K. Kosma, S. A. Trushin, W. Fuss, and W. E. Schmid, J. Phys. Chem. A 112, 7514 (2008)] reporting much shorter lifetimes than predicted by theory. Investigation of the TRPES indicates that the fast decay of the photoion yield originates from both energetic and electronic factors, with the energetic factor playing a larger role in shaping the signal.
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Affiliation(s)
- H Tao
- Department of Chemistry and PULSE Institute, Stanford University, Stanford, California 94305, USA
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Allison TK, Wright TW, Stooke AM, Khurmi C, van Tilborg J, Liu Y, Falcone RW, Belkacem A. Femtosecond spectroscopy with vacuum ultraviolet pulse pairs. OPTICS LETTERS 2010; 35:3664-3666. [PMID: 21042384 DOI: 10.1364/ol.35.003664] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We combine different wavelengths from an intense high-order harmonics source with variable delay at the focus of a split-mirror interferometer to conduct pump-probe experiments on gas-phase molecules. We report measurements of the time resolution (<44 fs) and spatial profiles (4 μm × 12 μm) at the focus of the apparatus. We demonstrate the utility of this two-color, high-order-harmonic technique by time resolving molecular hydrogen elimination from C(2)H(4) excited into its absorption band at 161 nm.
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Affiliation(s)
- T K Allison
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
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