1
|
Holzmeier F, Bello RY, Hervé M, Achner A, Baumann TM, Meyer M, Finetti P, Di Fraia M, Gauthier D, Roussel E, Plekan O, Richter R, Prince KC, Callegari C, Bachau H, Palacios A, Martín F, Dowek D. Control of H_{2} Dissociative Ionization in the Nonlinear Regime Using Vacuum Ultraviolet Free-Electron Laser Pulses. PHYSICAL REVIEW LETTERS 2018; 121:103002. [PMID: 30240272 DOI: 10.1103/physrevlett.121.103002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Indexed: 06/08/2023]
Abstract
The role of the nuclear degrees of freedom in nonlinear two-photon single ionization of H_{2} molecules interacting with short and intense vacuum ultraviolet pulses is investigated, both experimentally and theoretically, by selecting single resonant vibronic intermediate neutral states. This high selectivity relies on the narrow bandwidth and tunability of the pulses generated at the FERMI free-electron laser. A sustained enhancement of dissociative ionization, which even exceeds nondissociative ionization, is observed and controlled as one selects progressively higher vibronic states. With the help of ab initio calculations for increasing pulse durations, the photoelectron and ion energy spectra obtained with velocity map imaging allow us to identify new photoionization pathways. With pulses of the order of 100 fs, the experiment probes a timescale that lies between that of ultrafast dynamical processes and that of steady state excitations.
Collapse
Affiliation(s)
- F Holzmeier
- Institut des Sciences Moléculaires d'Orsay CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
- Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France
| | - R Y Bello
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - M Hervé
- Institut des Sciences Moléculaires d'Orsay CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - A Achner
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - T M Baumann
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - M Meyer
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - P Finetti
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - M Di Fraia
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - D Gauthier
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - E Roussel
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - O Plekan
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - K C Prince
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - C Callegari
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - H Bachau
- Centre des Lasers Intenses et Applications (UMR 5107 du CNRS-CEA-Université de Bordeaux), 351 Cours de la Libération, 33405 Talence cedex, France
| | - A Palacios
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - F Martín
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - D Dowek
- Institut des Sciences Moléculaires d'Orsay CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| |
Collapse
|
2
|
Glodic P, Zaouris D, Samartzis PC, Hafliðason A, Kvaran Á. Effect of a triplet to singlet state interaction on photofragmentation dynamics: highly excited states of HBr probed by VMI and REMPI as a case study. Phys Chem Chem Phys 2016; 18:26291-26299. [PMID: 27722295 DOI: 10.1039/c6cp04108f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Analysis of mass resolved spectra as well as velocity map images derived from resonance enhanced multiphoton ionization (REMPI) of HBr via resonance excitations to mixed Rydberg (6pπ 3Σ-(v' = 0)) and valence (ion-pair) (V 1Σ+(v' = m + 17)) states allows characterization of the effect of a triplet-to-singlet state interaction on further photoexcitation and photoionization processes. The analysis makes use of rotational spectra line shifts, line intensity alterations, kinetic energy release spectra as well as angular distributions. Energy-level-dependent state mixing of the resonance excited states is quantified and photoexcitation processes, leading to H+ formation, are characterized in terms of the states and fragmentation processes involved, depending on the state mixing.
Collapse
Affiliation(s)
- Pavle Glodic
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 71110 Heraklion, Greece
| | - Dimitris Zaouris
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 71110 Heraklion, Greece
| | - Peter C Samartzis
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 71110 Heraklion, Greece
| | - Arnar Hafliðason
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
| | - Ágúst Kvaran
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
| |
Collapse
|
3
|
Zaouris D, Kartakoullis A, Glodic P, Samartzis PC, Rafn Hróðmarsson H, Kvaran Á. Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr. Phys Chem Chem Phys 2015; 17:10468-77. [PMID: 25801122 DOI: 10.1039/c5cp00748h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoexcitation dynamics of the E((1)Σ(+)) (v' = 0) Rydberg state and the V((1)Σ(+)) (v') ion-pair vibrational states of HBr are investigated by velocity map imaging (VMI). H(+) photoions, produced through a number of vibrational and rotational levels of the two states were imaged and kinetic energy release (KER) and angular distributions were extracted from the data. In agreement with previous work, we found the photodissociation channels forming H*(n = 2) + Br((2)P3/2)/Br*((2)P1/2) to be dominant. Autoionization pathways leading to H(+) + Br((2)P3/2)/Br*((2)P1/2) via either HBr(+)((2)Π3/2) or HBr(+)*((2)Π1/2) formation were also present. The analysis of KER and angular distributions and comparison with rotationally and mass resolved resonance enhanced multiphoton ionization (REMPI) spectra revealed the excitation transition mechanisms and characteristics of states involved as well as the involvement of the E-V state interactions and their v' and J' dependence.
Collapse
Affiliation(s)
- Dimitris Zaouris
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 71110 Heraklion, Greece
| | | | | | | | | | | |
Collapse
|
5
|
Silva R, Gichuhi WK, Doyle MB, Winney AH, Suits AG. Photodissociation of heptane isomers and relative ionization efficiencies of butyl and propyl radicals at 157 nm. Phys Chem Chem Phys 2009; 11:4777-81. [PMID: 19492132 DOI: 10.1039/b823505h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report an ion imaging and time-of-flight mass spectroscopy study of the photodissociation of a variety of heptane isomers using 157 nm dissociation and ionization. Time-of-flight mass spectra show that C(3)H(7) + C(4)H(9) is the dominant detected product channel following one-color 157 nm dissociation/ionization of heptanes. The results further allow determination of the relative ionization efficiencies of 1- and 2-butyl and propyl radicals at 157 nm. Momentum matching for the two radical products indicates that, for the C3-C4 products, neutral dissociation followed by ionization is the main source of the detected signals. The images show isotropic angular distributions and the translational energy distributions peak at very low energy, with only approximately 0.3 eV or 8% of the available energy appearing in translation. This is consistent with dissociation from the ground state or low-lying triplet states following non-radiative electronic relaxation.
Collapse
Affiliation(s)
- Ruchira Silva
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | | | | | | | | |
Collapse
|
6
|
Romanescu C, Loock HP. Proton formation in 2+1 resonance enhanced multiphoton excitation of HCl and HBr via (Ω=0) Rydberg and ion-pair states. J Chem Phys 2007; 127:124304. [PMID: 17902900 DOI: 10.1063/1.2767259] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular beam cooled HCl was state selected by two-photon excitation of the V (1) summation operator(0(+)) [v=9,11-13,15], E (1) summation operator(0(+)) [v=0], and g (3) summation operator(-)(0(+)) [v=0] states through either the Q(0) or Q(1) lines of the respective (1,3) summation operator(0(+))<--<--X (1) summation operator(0(+)) transition. Similarly, HBr was excited to the V (1) summation operator(0(+)) [v=m+3, m+5-m+8], E (1) summation operator(0(+)) [v=0], and H (1) summation operator(0(+)) [v=0] states through the Q(0) or Q(1) lines. Following absorption of a third photon, protons were formed by three different mechanisms and detected using velocity map imaging. (1) H(*)(n=2) was formed in coincidence with (2)P(i) halogen atoms and subsequently ionized. For HCl, photodissociation into H(*)(n=2)+Cl((2)P(12)) was dominant over the formation of Cl((2)P(32)) and was attributed to parallel excitation of the repulsive [(2) (2)Pi4llambda] superexcited (Omega=0) states. For HBr, the Br((2)P(32))Br((2)P(12)) ratio decreases with increasing excitation energy. This indicates that both the [(3) (2)Pi(12)5llambda] and the [B (2) summation operator5llambda] superexcited (Omega=0) states contribute to the formation of H(*)(n=2). (2) For selected intermediate states HCl was found to dissociate into the H(+)+Cl(-) ion pair with over 20% relative yield. A mechanism is proposed by which a bound [A (2) summation operatornlsigma] (1) summation operator(0(+)) superexcited state acts as a gateway state to dissociation into the ion pair. (3) For all intermediate states, protons were formed by dissociation of HX(+)[v(+)] following a parallel, DeltaOmega=0, excitation. The quantum yield for the dissociation process was obtained using previously reported photoionization efficiency data and was found to peak at v(+)=6-7 for HCl and v(+)=12 for HBr. This is consistent with excitation of the repulsive A(2) summation operator(12) and (2) (2)Pi states of HCl(+), and the (3) (2)Pi state of HBr(+). Rotational alignment of the Omega=0(+) intermediate states is evident from the angular distribution of the excited H(*)(n=2) photofragments. This effect has been observed previously and was used here to verify the reliability of the measured spatial anisotropy parameters.
Collapse
|
8
|
Hobza P, Zahradník R, Müller-Dethlefs K. The World of Non-Covalent Interactions: 2006. ACTA ACUST UNITED AC 2006. [DOI: 10.1135/cccc20060443] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The review focusses on the fundamental importance of non-covalent interactions in nature by illustrating specific examples from chemistry, physics and the biosciences. Laser spectroscopic methods and both ab initio and molecular modelling procedures used for the study of non-covalent interactions in molecular clusters are briefly outlined. The role of structure and geometry, stabilization energy, potential and free energy surfaces for molecular clusters is extensively discussed in the light of the most advanced ab initio computational results for the CCSD(T) method, extrapolated to the CBS limit. The most important types of non-covalent complexes are classified and several small and medium size non-covalent systems, including H-bonded and improper H-bonded complexes, nucleic acid base pairs, and peptides and proteins are discussed with some detail. Finally, we evaluate the interpretation of experimental results in comparison with state of the art theoretical models: this is illustrated for phenol...Ar, the benzene dimer and nucleic acid base pairs. A review with 270 references.
Collapse
|
9
|
Ashfold MNR, Nahler NH, Orr-Ewing AJ, Vieuxmaire OPJ, Toomes RL, Kitsopoulos TN, Garcia IA, Chestakov DA, Wu SM, Parker DH. Imaging the dynamics of gas phase reactions. Phys Chem Chem Phys 2006; 8:26-53. [PMID: 16482242 DOI: 10.1039/b509304j] [Citation(s) in RCA: 240] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ion imaging methods are making ever greater impact on studies of gas phase molecular reaction dynamics. This article traces the evolution of the technique, highlights some of the more important breakthroughs with regards to improving image resolution and in image processing and analysis methods, and then proceeds to illustrate some of the many applications to which the technique is now being applied--most notably in studies of molecular photodissociation and of bimolecular reaction dynamics.
Collapse
|