1
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Sparling C, Ruget A, Ireland L, Kotsina N, Ghafur O, Leach J, Townsend D. The importance of molecular axis alignment and symmetry-breaking in photoelectron elliptical dichroism. J Chem Phys 2023; 159:214301. [PMID: 38038198 DOI: 10.1063/5.0180361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023] Open
Abstract
Photoelectron angular distributions (PADs) produced from the photoionization of chiral molecules using elliptically polarized light exhibit a forward/backward asymmetry with respect to the optical propagation direction. By recording these distributions using the velocity-map imaging (VMI) technique, the resulting photoelectron elliptical dichroism (PEELD) has previously been demonstrated as a promising spectroscopic tool for studying chiral molecules in the gas phase. The use of elliptically polarized laser pulses, however, produces PADs (and consequently, PEELD distributions) that do not exhibit cylindrical symmetry about the propagation axis. This leads to significant limitations and challenges when employing conventional VMI acquisition and data processing strategies. Using novel photoelectron image analysis methods based around Hankel transform reconstruction tomography and machine learning, however, we have quantified-for the first time-significant symmetry-breaking contributions to PEELD signals that are of a comparable magnitude to the symmetric terms in the multiphoton ionization of (1R,4R)-(+)- and (1S,4S)-(-)-camphor. This contradicts any assumptions that symmetry-breaking can be ignored when reconstructing VMI data. Furthermore, these same symmetry-breaking terms are expected to appear in any experiment where circular and linear laser fields are used together. This ionization scheme is particularly relevant for investigating dynamics in chiral molecules, but it is not limited to them. Developing a full understanding of these terms and the role they play in the photoionization of chiral molecules is of clear importance if the potential of PEELD and related effects for future practical applications is to be fully realized.
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Affiliation(s)
- Chris Sparling
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Alice Ruget
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Lewis Ireland
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Nikoleta Kotsina
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Omair Ghafur
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Jonathan Leach
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Dave Townsend
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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2
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Ganjitabar H, Hadidi R, Garcia GA, Nahon L, Powis I. Analysis of the volatile monoterpene composition of citrus essential oils by photoelectron spectroscopy employing continuously monitored dynamic headspace sampling. Analyst 2023; 148:6228-6240. [PMID: 37987708 DOI: 10.1039/d3an01448g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
A new photoelectron spectroscopic method permitting a quantitative analysis of the volatile headspace of several essential oils is presented and discussed. In particular, we focus on the monoterpene compounds, which are known to be the dominant volatile components in many such oils. The photoelectron spectra of the monoterpene constituents may be effectively isolated by accepting for analysis only those electrons that accompany the production of m/z = 136 ions, and by using low photon energies that restrict cation fragmentation. The monoterpene isomers are then identified and quantified by regression modelling using a library of terpene standard spectra. An advantage of this approach is that pre-concentration of the volatile vapour is not required, and all steps are performed at ambient temperature, avoiding the possible deleterious effects (such as isomerisation/decomposition) that may sometimes arise in gas chromatographic (GC) procedures. As a proof-of-principle demonstration, three citrus oils (lemon, lime, bergamot) are analysed with this approach and the results are compared with reported GC composition profiles obtained for these oils. Potential advantages of the methodology that include multiplex detection and real-time, in situ analysis are identified and discussed. Alternative and faster experimental implementations concerning laboratory-based ionization and detection schemes are proposed and considered, as is the possibility of a straightforward extension towards simultaneous determination of enantiomeric excesses.
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Affiliation(s)
- Hassan Ganjitabar
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Rim Hadidi
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Gif sur Yvette Cedex, France
| | - Gustavo A Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Gif sur Yvette Cedex, France
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Gif sur Yvette Cedex, France
| | - Ivan Powis
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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3
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Rouquet E, Roy Chowdhury M, Garcia GA, Nahon L, Dupont J, Lepère V, Le Barbu-Debus K, Zehnacker A. Induced photoelectron circular dichroism onto an achiral chromophore. Nat Commun 2023; 14:6290. [PMID: 37813848 PMCID: PMC10562374 DOI: 10.1038/s41467-023-42002-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/25/2023] [Indexed: 10/11/2023] Open
Abstract
An achiral chromophore can acquire a chiral spectroscopic signature when interacting with a chiral environment. This so-called induced chirality is documented in electronic or vibrational circular dichroism, which arises from the coupling between electric and magnetic transition dipoles. Here, we demonstrate that a chiroptical response is also induced within the electric dipole approximation by observing the asymmetric scattering of a photoelectron ejected from an achiral chromophore in interaction with a chiral host. In a phenol-methyloxirane complex, removing an electron from an achiral aromatic π orbital localised on the phenol moiety results in an intense and opposite photoelectron circular dichroism (PECD) for the two enantiomeric complexes with (R) and (S) methyloxirane, evidencing the long-range effect (~5 Å) of the scattering chiral potential. This induced chirality has important structural and analytical implications, discussed here in the context of growing interest in laser-based PECD, for in situ, real time enantiomer determination.
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Affiliation(s)
- Etienne Rouquet
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, F-91190, St Aubin, France
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | | | - Gustavo A Garcia
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, F-91190, St Aubin, France
| | - Laurent Nahon
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, F-91190, St Aubin, France.
| | - Jennifer Dupont
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | - Valéria Lepère
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | - Katia Le Barbu-Debus
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405, Orsay, France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405, Orsay, France.
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4
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Sparling C, Crane SW, Ireland L, Anderson R, Ghafur O, Greenwood JB, Townsend D. Velocity-map imaging of photoelectron circular dichroism in non-volatile molecules using a laser-based desorption source. Phys Chem Chem Phys 2023; 25:6009-6015. [PMID: 36752555 DOI: 10.1039/d2cp05880d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
We present an initial demonstration of a velocity-map imaging (VMI) experiment using a back-irradiation laser-based desorption source directly integrated into the electrode assembly. This has the potential to greatly expand the utility of the popular VMI approach by permitting its use with high density plumes of non-volatile molecular samples. Photoelectron circular dichroism measurements on the phenylalanine molecule using 400 nm multiphoton ionization are used to illustrate this novel method, revealing forward-backward emission asymmetries on the order of 7%.
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Affiliation(s)
- Chris Sparling
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Stuart W Crane
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Lewis Ireland
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Ross Anderson
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Omair Ghafur
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Jason B Greenwood
- School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN, UK
| | - Dave Townsend
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. .,Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
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5
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Ayuso D, Ordonez AF, Smirnova O. Ultrafast chirality: the road to efficient chiral measurements. Phys Chem Chem Phys 2022; 24:26962-26991. [PMID: 36342056 PMCID: PMC9673685 DOI: 10.1039/d2cp01009g] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/20/2022] [Indexed: 08/20/2023]
Abstract
Today we are witnessing the electric-dipole revolution in chiral measurements. Here we reflect on its lessons and outcomes, such as the perspective on chiral measurements using the complementary principles of "chiral reagent" and "chiral observer", the hierarchy of scalar, vectorial and tensorial enantio-sensitive observables, the new properties of the chiro-optical response in the ultrafast and non-linear domains, and the geometrical magnetism associated with the chiral response in photoionization. The electric-dipole revolution is a landmark event. It has opened routes to extremely efficient enantio-discrimination with a family of new methods. These methods are governed by the same principles but work in vastly different regimes - from microwaves to optical light; they address all molecular degrees of freedom - electronic, vibrational and rotational, and use flexible detection schemes, i.e. detecting photons or electrons, making them applicable to different chiral phases, from gases to liquids to amorphous solids. The electric-dipole revolution has also enabled enantio-sensitive manipulation of chiral molecules with light. This manipulation includes exciting and controlling ultrafast helical currents in vibronic states of chiral molecules, enantio-sensitive control of populations in electronic, vibronic and rotational molecular states, and opens the way to efficient enantio-separation and enantio-sensitive trapping of chiral molecules. The word "perspective" has two meanings: an "outlook" and a "point of view". In this perspective article, we have tried to cover both meanings.
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Affiliation(s)
- David Ayuso
- Max-Born-Institut, 12489 Berlin, Germany
- Imperial College London, SW7 2AZ London, UK.
| | - Andres F Ordonez
- Max-Born-Institut, 12489 Berlin, Germany
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain.
| | - Olga Smirnova
- Max-Born-Institut, 12489 Berlin, Germany
- Technische Universität Berlin, 10623 Berlin, Germany.
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6
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Svoboda V, Ram NB, Baykusheva D, Zindel D, Waters MDJ, Spenger B, Ochsner M, Herburger H, Stohner J, Wörner HJ. Femtosecond photoelectron circular dichroism of chemical reactions. SCIENCE ADVANCES 2022; 8:eabq2811. [PMID: 35857523 PMCID: PMC9286499 DOI: 10.1126/sciadv.abq2811] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Understanding the chirality of molecular reaction pathways is essential for a broad range of fundamental and applied sciences. However, the current ability to probe chirality on the time scale of primary processes underlying chemical reactions remains very limited. Here, we demonstrate time-resolved photoelectron circular dichroism (TRPECD) with ultrashort circularly polarized vacuum-ultraviolet (VUV) pulses from a tabletop source. We demonstrate the capabilities of VUV-TRPECD by resolving the chirality changes in time during the photodissociation of atomic iodine from two chiral molecules. We identify several general key features of TRPECD, which include the ability to probe dynamical chirality along the complete photochemical reaction path, the sensitivity to the local chirality of the evolving scattering potential, and the influence of electron scattering off dissociating photofragments. Our results are interpreted by comparison with high-level ab-initio calculations of transient PECDs from molecular photoionization calculations. Our experimental and theoretical techniques define a general approach to femtochirality.
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Affiliation(s)
- Vít Svoboda
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Niraghatam Bhargava Ram
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
- Department of Physics, Indian Institute of Science Education and Research–Bhopal, Bhauri, Bhopal 462066, India
| | | | - Daniel Zindel
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Max D. J. Waters
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Benjamin Spenger
- Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences, Wädenswil 8820, Switzerland
| | - Manuel Ochsner
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Holger Herburger
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Jürgen Stohner
- Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences, Wädenswil 8820, Switzerland
| | - Hans Jakob Wörner
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
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7
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Fehre K, Trinter F, Novikovskiy NM, Grundmann S, Tsitsonis D, Eckart S, Bauer L, Hilzinger M, Jahnke T, Dörner R, Demekhin PV, Schöffler MS. Influence of the emission site on the photoelectron circular dichroism in trifluoromethyloxirane. Phys Chem Chem Phys 2022; 24:13597-13604. [PMID: 35621377 DOI: 10.1039/d2cp00143h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a joint experimental and theoretical study of the differential photoelectron circular dichroism (PECD) in inner-shell photoionization of uniaxially oriented trifluoromethyloxirane. By adjusting the photon energy of the circularly polarized synchrotron radiation, we address 1s-photoionization of the oxygen, different carbon, and all fluorine atoms. The photon energies were chosen such that in all cases electrons with a similar kinetic energy of about 11 eV are emitted. Employing coincident detection of electrons and fragment ions, we concentrate on identical molecular fragmentation channels for all of the electron-emitter scenarios. Thereby, we systematically examine the influence of the emission site of the photoelectron wave on the differential PECD. We observe large differences in the PECD signals. The present experimental results are supported by corresponding relaxed-core Hartree-Fock calculations.
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Affiliation(s)
- Kilian Fehre
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Florian Trinter
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany. .,Molecular Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Nikolay M Novikovskiy
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany. .,Institute of Physics, Southern Federal University, 344090 Rostov-on-Don, Russia
| | - Sven Grundmann
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Dimitrios Tsitsonis
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Sebastian Eckart
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Leonie Bauer
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Maria Hilzinger
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Till Jahnke
- European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Reinhard Dörner
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
| | - Philipp V Demekhin
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany.
| | - Markus S Schöffler
- Institut für Kernphysik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
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8
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Dupont J, Lepère V, Zehnacker A, Hartweg S, Garcia GA, Nahon L. Photoelectron Circular Dichroism as a Signature of Subtle Conformational Changes: The Case of Ring Inversion in 1-Indanol. J Phys Chem Lett 2022; 13:2313-2320. [PMID: 35245057 DOI: 10.1021/acs.jpclett.2c00074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Chirality plays a fundamental role in the molecular recognition processes. Molecular flexibility is also crucial in molecular recognition, allowing the interacting molecules to adjust their structures and hence optimize the interaction. Methods probing simultaneously chirality and molecular conformation are therefore crucially needed. Taking advantage of a possible control in the gas phase of the conformational distribution between the equatorial and axial conformers resulting from a ring inversion in jet-cooled 1-indanol, we demonstrate here the sensitivity of valence-shell photoelectron circular dichroism (PECD) to both chirality and subtle conformational changes, in a case where the photoelectron spectra of the two conformers are identical. For the highest occupied orbital, we observe a dramatic inversion of the PECD-induced photoelectron asymmetries, while the photoionization cross-section and usual anisotropy (β) parameter are completely insensitive to conformational isomerism. Such a sensitivity is a major asset for the ongoing developments of PECD-based techniques as a sensitive chiral (bio)chemical analytical tool in the gas phase.
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Affiliation(s)
- Jennifer Dupont
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Valéria Lepère
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Sebastian Hartweg
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
| | - Gustavo A Garcia
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
| | - Laurent Nahon
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
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9
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Beauvarlet S, Bloch E, Rajak D, Descamps D, Fabre B, Petit S, Pons B, Mairesse Y, Blanchet V. Photoelectron elliptical dichroism spectroscopy of resonance-enhanced multiphoton ionization via the 3s, 3p and 3d Rydberg series in fenchone. Phys Chem Chem Phys 2022; 24:6415-6427. [PMID: 35113091 DOI: 10.1039/d1cp05618b] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The resonance-enhanced multiphoton ionization of chiral molecules by elliptically polarized laser pulses produces photoelectron angular distributions that are forward/backward asymmetric with respect to the light propagation axis. We investigate this photoelectron elliptical dichroism in the (2 + 1)-photon ionization of fenchone molecules, using wavelength tunable femtosecond UV pulses. We show that the photoelectron elliptical asymmetry is extremely sensitive to the intermediate resonant states involved in the ionization process, and enables electronic couplings to be revealed that do not show up so clearly when using circularly polarized light.
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Affiliation(s)
- Sandra Beauvarlet
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Etienne Bloch
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Debobrata Rajak
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Dominique Descamps
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Baptiste Fabre
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Stéphane Petit
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Bernard Pons
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Yann Mairesse
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
| | - Valérie Blanchet
- Université de Bordeaux - CNRS - CEA, CELIA, UMR 5107, F33405 Talence, France.
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10
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Sparling C, Ruget A, Leach J, Townsend D. Arbitrary image reinflation: A deep learning technique for recovering 3D photoproduct distributions from a single 2D projection. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:023303. [PMID: 35232150 DOI: 10.1063/5.0082744] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Many charged particle imaging measurements rely on the inverse Abel transform (or related methods) to reconstruct three-dimensional (3D) photoproduct distributions from a single two-dimensional (2D) projection image. This technique allows for both energy- and angle-resolved information to be recorded in a relatively inexpensive experimental setup, and its use is now widespread within the field of photochemical dynamics. There are restrictions, however, as cylindrical symmetry constraints on the overall form of the distribution mean that it can only be used with a limited range of laser polarization geometries. The more general problem of reconstructing arbitrary 3D distributions from a single 2D projection remains open. Here, we demonstrate how artificial neural networks can be used as a replacement for the inverse Abel transform and-more importantly-how they can be used to directly "reinflate" 2D projections into their original 3D distributions, even in cases where no cylindrical symmetry is present. This is subject to the simulation of appropriate training data based on known analytical expressions describing the general functional form of the overall anisotropy. Using both simulated and real experimental data, we show how our arbitrary image reinflation (AIR) neural network can be utilized for a range of different examples, potentially offering a simple and flexible alternative to more expensive and complicated 3D imaging techniques.
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Affiliation(s)
- Chris Sparling
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Alice Ruget
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Jonathan Leach
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Dave Townsend
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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11
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Lehmann CS, Botros D, Weitzel KM. Coincident measurement of photo-ion circular dichroism and photo-electron circular dichroism on 1-Phenylethylamine. Phys Chem Chem Phys 2022; 24:15904-15911. [DOI: 10.1039/d2cp01418a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we report the coincident measurement of the PICD and PECD effect in 1-Phenylethylamine upon multiphoton ionisation. Photo-ion circular dichroism (PICD) and photo-electron circular dichroism (PECD) are both methods to...
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12
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Lee HG, Ranecky ST, Vasudevan S, Ladda N, Rosen T, Das S, Ghosh J, Braun H, Reich DM, Senftleben A, Baumert T. Pulse length dependence of photoelectron circular dichroism. Phys Chem Chem Phys 2022; 24:27483-27494. [DOI: 10.1039/d2cp03202c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We investigated photoelectron circular dichroism (PECD) using pulses with various durations. From the experiment with fenchone, we found constancy of the PECD over a wide range of pulse durations and estimated lifetimes of internal conversions.
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Affiliation(s)
- Han-gyeol Lee
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Simon T. Ranecky
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Sudheendran Vasudevan
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Nicolas Ladda
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Tonio Rosen
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Sagnik Das
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Jayanta Ghosh
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Hendrike Braun
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Daniel M. Reich
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Arne Senftleben
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Thomas Baumert
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
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13
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Malerz S, Haak H, Trinter F, Stephansen AB, Kolbeck C, Pohl M, Hergenhahn U, Meijer G, Winter B. A setup for studies of photoelectron circular dichroism from chiral molecules in aqueous solution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:015101. [PMID: 35104975 DOI: 10.1063/5.0072346] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
We present a unique experimental design that enables the measurement of photoelectron circular dichroism (PECD) from chiral molecules in aqueous solution. The effect is revealed from the intensity difference of photoelectron emission into a backward-scattering angle relative to the photon propagation direction when ionizing with circularly polarized light of different helicity. This leads to asymmetries (normalized intensity differences) that depend on the handedness of the chiral sample and exceed the ones in conventional dichroic mechanisms by orders of magnitude. The asymmetry is largest for photon energies within several electron volts above the ionization threshold. A primary aim is to explore the effect of hydration on PECD. The modular and flexible design of our experimental setup EASI (Electronic structure from Aqueous Solutions and Interfaces) also allows for detection of more common photoelectron angular distributions, requiring distinctively different detection geometries and typically using linearly polarized light. A microjet is used for liquid-sample delivery. We describe EASI's technical features and present two selected experimental results, one based on synchrotron-light measurements and the other performed in the laboratory, using monochromatized He-II α radiation. The former demonstrates the principal effectiveness of PECD detection, illustrated for prototypic gas-phase fenchone. We also discuss the first data from liquid fenchone. In the second example, we present valence photoelectron spectra from liquid water and NaI aqueous solution, here obtained from a planar-surface microjet (flatjet). This new development features a more favorable symmetry for angle-dependent photoelectron measurements.
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Affiliation(s)
- Sebastian Malerz
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Henrik Haak
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Florian Trinter
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Anne B Stephansen
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Claudia Kolbeck
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Marvin Pohl
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Uwe Hergenhahn
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Gerard Meijer
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Bernd Winter
- Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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14
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Singh DP, Thompson JOF, Reid KL, Powis I. Influence of Vibrational Excitation and Nuclear Dynamics in Multiphoton Photoelectron Circular Dichroism of Fenchone. J Phys Chem Lett 2021; 12:11438-11443. [PMID: 34792356 DOI: 10.1021/acs.jpclett.1c03231] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report photoelectron circular dichroism of S-(+)-fenchone enantiomers recorded with state-state vibrational level resolution using picosecond laser (2 + 1) resonance enhanced multiphoton ionization via 3s and 3p Rydberg intermediate states. The 3p state decays to the 3s state on a picosecond time scale so that, above the 3p Rydberg excitation threshold, ionization of vibrationally hot 3s states competes with direct 3p-1 ionization. Complex vibronic dynamics of the 3p → 3s internal conversion weaken the Rydberg Δv = 0 propensity rule in both the 3p-1 and 3s-1 ionization channels. Large variations of the forward-backward chiral asymmetry factors are observed between the Δv = 0 and Δv > 0 vibrational transitions, including dramatic swings from up to ±17%. Such changes of sign indicate complete reversal of the preferred direction for photoelectron emission in the laboratory frame, associated with vibrational motion. These asymmetry switches easily exceed the amplitude and frequency of such vibrationally induced flips previously observed in single photon ionization.
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Affiliation(s)
- Dhirendra P Singh
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - James O F Thompson
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - Katharine L Reid
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - Ivan Powis
- School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, U.K
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15
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Sparling C, Ruget A, Kotsina N, Leach J, Townsend D. Artificial Neural Networks for Noise Removal in Data-Sparse Charged Particle Imaging Experiments. Chemphyschem 2021; 22:76-82. [PMID: 33206447 DOI: 10.1002/cphc.202000808] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/24/2020] [Indexed: 11/07/2022]
Abstract
We present the first demonstration of artificial neural networks (ANNs) for the removal of Poissonian noise in charged particle imaging measurements with very low overall counts. The approach is successfully applied to both simulated and real experimental image data relating to the detection of photoions/photoelectrons in unimolecular photochemical dynamics studies. Specific examples consider the multiphoton ionization of pyrrole and (S)-camphor. Our results reveal an extremely high level of performance, with the ANNs transforming images that are unusable for any form of quantitative analysis into statistically reliable data with an impressive similarity to benchmark references. Given the widespread use of charged particle imaging methods within the chemical dynamics community, we anticipate that the use of ANNs has significant potential impact - particularly, for example, when working in the limit of very low absorption/photoionization cross-sections, or when attempting to reliably extract subtle image features originating from phenomena such as photofragment vector correlations or photoelectron circular dichroism.
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Affiliation(s)
- Chris Sparling
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Alice Ruget
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Nikoleta Kotsina
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Jonathan Leach
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Dave Townsend
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.,Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
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16
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Singh DP, De Oliveira N, Garcia GA, Vredenborg A, Powis I. Experimental and Theoretical Investigation of the 3sp(d) Rydberg States of Fenchone by Polarized Laser Resonance-Enhanced-Multiphoton-Ionization and Fourier Transform VUV Absorption Spectroscopy. Chemphyschem 2020; 21:2468-2483. [PMID: 32893958 DOI: 10.1002/cphc.202000365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 09/04/2020] [Indexed: 11/08/2022]
Abstract
The VUV absorption spectrum of fenchone is re-examined using synchrotron radiation Fourier transform spectrometry, revealing new vibrational structure. Picosecond laser (2+1) resonance enhanced multiphoton ionization (REMPI) spectroscopy complements this, providing an alternative view of the 3spd Rydberg excitation region. These spectra display broadly similar appearance, with minor differences that are largely explained by referring to calculated one- and two-photon electronic excitation cross-sections. Both show good agreement with Franck-Condon simulations of the relevant vibrational structures. Parent ion REMPI ionization yields with both femtosecond and picosecond excitation laser pulses are studied as a function of laser polarization and intensity, the latter providing insight into the relative two-photon excitation and one-photon ionization rates. The experimental circular-linear dichroism observed in the parent ion yields varies strongly between the 3s and 3p Rydberg states, in good overall agreement with the calculated two-photon excitation circular-linear dichroism, while corroborating other evidence that the 3pz sub-state plays no more than a very minor role in the (2+1) REMPI spectrum. Vibrationally resolved photoelectron spectra are recorded with picosecond pulse duration (2+1) REMPI at selected intermediate vibrational excitations. The 3s intermediate state displays a very strong Δv=0 propensity on ionization, but the 3p intermediate evidences more complex vibronic dynamics, and we infer some 3p→3s internal conversion prior to ionization.
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Affiliation(s)
- Dhirendra P Singh
- School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Nelson De Oliveira
- Synchrotron SOLEIL, l'Orme des Merisiers, 91192 Cedex, Saint-Aubin BP 48, Gif-sur-Yvette, France
| | - Gustavo A Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers, 91192 Cedex, Saint-Aubin BP 48, Gif-sur-Yvette, France
| | - Arno Vredenborg
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, Netherlands
- MassSpecpecD BV, Langenkampweg 101, 7522 LL, Enschede, Netherlands
| | - Ivan Powis
- School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, U.K
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17
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Ganjitabar H, Singh DP, Chapman R, Gardner A, Minns RS, Powis I, Reid KL, Vredenborg A. The role of the intermediate state in angle-resolved photoelectron studies using (2 + 1) resonance-enhanced multiphoton ionization of the chiral terpenes, α-pinene and 3-carene. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1808907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Hassan Ganjitabar
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Dhirendra P. Singh
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Richard Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Adrian Gardner
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
- Stephenson Institute for Renewable Energy and the Department of Chemistry, University of Liverpool, Liverpool, UK
| | - Russell S. Minns
- School of Chemistry, University of Southampton, Highfield, Southampton, UK
| | - Ivan Powis
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Katharine L. Reid
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Arno Vredenborg
- Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, The Netherlands
- MassSpecpecD BV, Enschede, The Netherlands
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18
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Comby A, Bond CMM, Bloch E, Descamps D, Fabre B, Petit S, Mairesse Y, Greenwood JB, Blanchet V. Using photoelectron elliptical dichroism (PEELD) to determine real-time variation of enantiomeric excess. Chirality 2020; 32:1225-1233. [PMID: 32700433 DOI: 10.1002/chir.23267] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 06/12/2020] [Accepted: 06/23/2020] [Indexed: 11/08/2022]
Abstract
In this work, the photoionization of chiral molecules by an elliptically polarized, high repetition rate, femtosecond laser is probed. The resulting 3D photoelectron angular distribution shows a strong forward-backward asymmetry, which is highly dependent not only on the molecular structure but also on the ellipticity of the laser pulse. By continuously varying the laser ellipticity, we can observe molecular and enantiomer changes in real time at a previously unseen speed and precision. The technique allows enantiomeric excess of a pure compound to be measured with a 5% precision within 3 s, and a 10-min acquisition yields a precision of 0.4%. The isomers camphor and fenchone can be easily distinguished, unlike with conventional mass spectrometry. Preliminary results for the pharmaceutically interesting ibuprofen are also given, showing the capability of photoionization as a means of distinguishing larger molecular systems.
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Affiliation(s)
- Antoine Comby
- CELIA-CNRS-CEA, Université de Bordeaux, Talence, France
| | | | - Etienne Bloch
- CELIA-CNRS-CEA, Université de Bordeaux, Talence, France
| | | | | | | | - Yann Mairesse
- CELIA-CNRS-CEA, Université de Bordeaux, Talence, France
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19
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Lehmann CS, Weitzel KM. Coincident measurement of photo-ion circular dichroism and photo-electron circular dichroism. Phys Chem Chem Phys 2020; 22:13707-13712. [DOI: 10.1039/d0cp01376e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photo-ion circular dichroism (PICD) and photo-electron circular dichroism (PECD) have been measured for the first time simultaneously in a coincidence experiment detecting the chirality of R- and S-Methyloxirane.
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20
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Goetz RE, Koch CP, Greenman L. Perfect control of photoelectron anisotropy for randomly oriented ensembles of molecules by XUV REMPI and polarization shaping. J Chem Phys 2019; 151:074106. [PMID: 31438691 DOI: 10.1063/1.5111362] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report two schemes to generate perfect anisotropy in the photoelectron angular distribution of a randomly oriented ensemble of polyatomic molecules. In order to exert full control over the anisotropy of photoelectron emission, we exploit interferences between single-photon pathways and a manifold of resonantly enhanced two-photon pathways. These are shown to outperform nonsequential (ω, 2ω) bichromatic phase control for the example of CHFClBr molecules. We are able to optimize pulses that yield anisotropic photoelectron emission thanks to a very efficient calculation of photoelectron momentum distributions. This is accomplished by combining elements of quantum chemistry, variational scattering theory, and time-dependent perturbation theory.
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Affiliation(s)
- R Esteban Goetz
- Department of Physics, Kansas State University, 116 Cardwell Hall, 1228 N. 17th St., Manhattan, Kansas 66506-2601, USA
| | - Christiane P Koch
- Theoretische Physik, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
| | - Loren Greenman
- Department of Physics, Kansas State University, 116 Cardwell Hall, 1228 N. 17th St., Manhattan, Kansas 66506-2601, USA
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21
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Kartouzian A. Spectroscopy for model heterogeneous asymmetric catalysis. Chirality 2019; 31:641-657. [PMID: 31318108 DOI: 10.1002/chir.23113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/02/2019] [Indexed: 12/31/2022]
Abstract
Heterogeneous catalysis has vastly benefited from investigations performed on model systems under well-controlled conditions. The application of most of the techniques utilized for such studies is not feasible for asymmetric reactions as enantiomers possess identical physical and chemical properties unless while interacting with polarized light and other chiral entities. A thorough investigation of a heterogeneous asymmetric catalytic process should include probing the catalyst prior to, during, and after the reaction as well as the analysis of reaction products to evaluate the achieved enantiomeric excess. I present recent studies that demonstrate the strength of chiroptical spectroscopic methods to tackle the challenges in investigating model heterogeneous asymmetric catalysis covering all the abovementioned aspects.
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Affiliation(s)
- Aras Kartouzian
- Lehrstuhl für physikalische Chemie, Catalysis Research Center, Technische Universität München, Garching bei München, Germany
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22
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Kastner A, Ring T, Braun H, Senftleben A, Baumert T. Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser. Chemphyschem 2019; 20:1416-1419. [PMID: 30972931 DOI: 10.1002/cphc.201900289] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/02/2019] [Indexed: 11/09/2022]
Abstract
Photoelectron circular dichroism (PECD) is a fascinating phenomenon both from a fundamental science aspect but also due to its emerging role as a highly sensitive analytic tool for chiral recognition in the gas phase. PECD has been studied with single-photon as well as multi-photon ionization. The latter has been investigated in the short pulse limit with femtosecond laser pulses, where ionization can be thought of as an instantaneous process. In this contribution, we demonstrate that multi-photon PECD still can be observed when using an ultra-violet nanosecond pulse to ionize chiral showcase fenchone molecules. Compared to femtosecond ionization, the magnitude of PECD is similar, but the lifetime of intermediate molecular states imprints itself in the photoelectron spectra. Being able to use an industrial nanosecond laser to investigate PECD furthermore reduces the technical requirements to apply PECD in analytical chemistry.
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Affiliation(s)
- Alexander Kastner
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Tom Ring
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Hendrike Braun
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Arne Senftleben
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Thomas Baumert
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
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23
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Demekhin PV, Artemyev AN, Kastner A, Baumert T. Photoelectron Circular Dichroism with Two Overlapping Laser Pulses of Carrier Frequencies ω and 2ω Linearly Polarized in Two Mutually Orthogonal Directions. PHYSICAL REVIEW LETTERS 2018; 121:253201. [PMID: 30608808 DOI: 10.1103/physrevlett.121.253201] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/09/2018] [Indexed: 05/20/2023]
Abstract
Using a model methanelike chiral system, we theoretically demonstrate a possibility to access photoelectron circular dichroism (PECD) by a single experiment with two overlapping laser pulses of carrier frequencies ω and 2ω, which are linearly polarized in two mutually orthogonal directions. Depending on the relative phase, the resulting electric field can be tailored to have two different rotational directions in the upper and lower hemispheres along the polarization of the ω pulse. We predict a strong forward-backward asymmetry in the emission of photoelectrons from randomly oriented samples, which has an opposite sign in the upper and lower hemispheres. The predicted PECD effect is phase and enantiomer sensitive, providing new insight in this fascinating fundamental phenomenon. The effect can be optimized by varying relative intensities of the pulses.
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Affiliation(s)
- Philipp V Demekhin
- Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Anton N Artemyev
- Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Alexander Kastner
- Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Thomas Baumert
- Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
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24
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Comby A, Bloch E, Bond CMM, Descamps D, Miles J, Petit S, Rozen S, Greenwood JB, Blanchet V, Mairesse Y. Real-time determination of enantiomeric and isomeric content using photoelectron elliptical dichroism. Nat Commun 2018; 9:5212. [PMID: 30523259 PMCID: PMC6283843 DOI: 10.1038/s41467-018-07609-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/09/2018] [Indexed: 11/09/2022] Open
Abstract
The fast and accurate analysis of chiral chemical mixtures is crucial for many applications but remains challenging. Here we use elliptically-polarized femtosecond laser pulses at high repetition rates to photoionize chiral molecules. The 3D photoelectron angular distribution produced provides molecular fingerprints, showing a strong forward-backward asymmetry which depends sensitively on the molecular structure and degree of ellipticity. Continuously scanning the laser ellipticity and analyzing the evolution of the rich, multi-dimensional molecular signatures allows us to observe real-time changes in the chemical and chiral content present with unprecedented speed and accuracy. We measure the enantiomeric excess of a compound with an accuracy of 0.4% in 10 min acquisition time, and follow the evolution of a mixture with an accuracy of 5% with a temporal resolution of 3 s. This method is even able to distinguish isomers, which cannot be easily distinguished by mass-spectrometry.
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Affiliation(s)
- A Comby
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France
| | - E Bloch
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France
| | - C M M Bond
- School of Maths and Physics, Queen's University, Belfast, BT7 INN, UK
| | - D Descamps
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France
| | - J Miles
- School of Maths and Physics, Queen's University, Belfast, BT7 INN, UK
| | - S Petit
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France
| | - S Rozen
- Weizmann Institute of Science, Rehovot, 76100, Israel
| | - J B Greenwood
- School of Maths and Physics, Queen's University, Belfast, BT7 INN, UK
| | - V Blanchet
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France
| | - Y Mairesse
- Université de Bordeaux - CNRS - CEA, CELIA, UMR5107, F33405, Talence, France.
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25
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Beaulieu S, Comby A, Descamps D, Petit S, Légaré F, Fabre B, Blanchet V, Mairesse Y. Multiphoton photoelectron circular dichroism of limonene with independent polarization state control of the bound-bound and bound-continuum transitions. J Chem Phys 2018; 149:134301. [DOI: 10.1063/1.5042533] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S. Beaulieu
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
- Institut National de la Recherche Scientifique, Centre EMT, Varennes, Quebec J3X 1S2,
Canada
| | - A. Comby
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
| | - D. Descamps
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
| | - S. Petit
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
| | - F. Légaré
- Institut National de la Recherche Scientifique, Centre EMT, Varennes, Quebec J3X 1S2,
Canada
| | - B. Fabre
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
| | - V. Blanchet
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
| | - Y. Mairesse
- Université de Bordeaux—CNRS—CEA, CELIA, UMR5107, F33405 Talence, France
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26
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Rafiee Fanood MM, Ganjitabar H, Garcia GA, Nahon L, Turchini S, Powis I. Intense Vibronic Modulation of the Chiral Photoelectron Angular Distribution Generated by Photoionization of Limonene Enantiomers with Circularly Polarized Synchrotron Radiation. Chemphyschem 2018; 19:921-933. [PMID: 29266631 DOI: 10.1002/cphc.201701248] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Indexed: 11/11/2022]
Abstract
Photoionization of the chiral monoterpene limonene has been investigated using polarized synchrotron radiation between the adiabatic ionization threshold, 8.505 and 23.5 eV. A rich vibrational structure is seen in the threshold photoelectron spectrum and is interpreted using a variety of computational methods. The corresponding photoelectron circular dichroism-measured in the photoelectron angular distribution as a forward-backward asymmetry with respect to the photon direction-was found to be strongly dependent on the vibronic structure appearing in the photoelectron spectra, with the observed asymmetry even switching direction in between the major vibrational peaks. This effect can be ultimately attributed to the sensitivity of this dichroism to small phase shifts between adjacent partial waves of the outgoing photoelectron. These observations have implications for potential applications of this chiroptical technique, where the enantioselective analysis of monoterpene components is of particular interest.
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Affiliation(s)
- Mohammad M Rafiee Fanood
- LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.,Current address: Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Hassan Ganjitabar
- School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Gustavo A Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France
| | - Stefano Turchini
- Istituto Struttura della Materia-CNR (ISM-CNR), Via del Fosso del Cavaliere 100, 00133, Roma, Italy
| | - Ivan Powis
- School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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