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Spectroscopic characterization of transition metal compounds by degenerate and two-color resonant four-wave mixing

Applicant Radi Peter
Number 153170
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Physical Chemistry
Start/End 01.07.2014 - 30.09.2017
Approved amount 350'838.00
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All Disciplines (2)

Discipline
Physical Chemistry
Inorganic Chemistry

Keywords (7)

catalysis; free jet; transition metal clusters; transition metal dimers; four-wave mixing; spectroscopy; laser-vaporization sources

Lay Summary (German)

Lead
Die elementaren katalytischen Reaktionsmechanismen von Legierungen sind ungenügend beschrieben. In diesem Projekt wird eine unkonventionelle nicht-lineare spektroskopische Methode verwendet, um die elektronischen Strukturen und chemischen Bindungen von kleinen heteronuklearen Molekülen und Clustern, die aus Übergangsmetallen bestehen, zu untersuchen.
Lay summary

Mit Hilfe von konventionellen spektroskopischen Methoden wie etwa Multiphoton-Ionisation, laser-induzierter Fluoreszenz und etwas weniger häufig verwendet 'cavity-ring down' und 'intra-cavity laser absorption' wurde die elektronische Struktur und chemischen Bindungseigenschaften von vielen homonuklearen Dimeren und kleinen Clustern untersucht und weitgehend charakterisiert. Die katalytische Aktivität wird im Wesentlichen durch die hohe Dichte von tiefliegenden elektronischen Zuständen bestimmt. Diese Zustände interagieren auf komplexe Weise um Metall-Metall und Metall-Ligand Bindungen zu bilden. Heteronukleare Dimere und Cluster sind dagegen weniger häufig untersucht worden. Um die dichte und komplizierte elektronische Struktur dieser Teilchen aufzuklären, wird hier eine nicht-lineare spektroskopische Methode eingesetzt: Vier-Wellen-Mischen. Wir haben in den vorgängigen Projekten gezeigt, dass die Technik (i) in der kontrollierten Umgebung eines Molekularstrahles eingesetzt werden kann, dass sie (ii) sich eignet um nicht-fluoreszierende Moleküle mit kurzen Lebensdauern zu untersuchen und dass sie (iii) die Möglichkeit eröffnet, optische Doppelresonanz-Experimente durchzuführen. Die letzte Eigenschaft ist von bedeutendem Vorteil für Untersuchungen von dichten und komplexen Spektren, die typischerweise in Experimenten mit Übergangsmetall-Dimeren und Clustern beobachtet werden.

Experimente zeigen, dass reaktive Zentren und defekte Stellen auf der Oberfläche von katalytisch aktiven Materialien eine wesentliche Rolle spielen. Die Ladungsdichte und -verteilung kann mit diesen kleinen Teilchen und Clustern imitiert und untersucht werden. Resultate aus solchen Messungen werden wesentlich zum Verständnis der elementaren Reaktionschritte von katalytischen Prozessen beitragen.

Direct link to Lay Summary Last update: 29.07.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Identification of a new low energy 1u state in dicopper with resonant four-wave mixing
Visser Bradley Beck Martin Bornhauser Peter, Knopp Gregor van Bokhoven Jeroen, Marquardt Roberto Gourlaouen Christoph Radi Peter (2017), Identification of a new low energy 1u state in dicopper with resonant four-wave mixing, in Journal of Chemical Physics, 147(21), 214308-1-214308-10.
Rovibrational Characterization of High-Lying Electronic States of Cu 2 by Double-Resonant Nonlinear Spectroscopy
Beck M., Visser B., Bornhauser P., Knopp G., van Bokhoven J. A., Radi P. P. (2017), Rovibrational Characterization of High-Lying Electronic States of Cu 2 by Double-Resonant Nonlinear Spectroscopy, in The Journal of Physical Chemistry A, 121(44), 8448-8452.
Line space theory of Resonant Four-Wave Mixing: New prospects for all-optical studies of photofragment states
Kouzov A.P., Radi P.P. (2017), Line space theory of Resonant Four-Wave Mixing: New prospects for all-optical studies of photofragment states, in Chemical Physics Letters, 673, 103-107.
Experimental and theoretical investigation of the vibrational band structure of the 1(5)Pi(u)-1 (5)Pi(g) high-spin system of C-2
Bornhauser P., Visser B., Beck M., Knopp G., van Bokhoven J. A., Marquardt R., Radi P. P. (2017), Experimental and theoretical investigation of the vibrational band structure of the 1(5)Pi(u)-1 (5)Pi(g) high-spin system of C-2, in JOURNAL OF CHEMICAL PHYSICS, 146(11), 114309-1-114309-13.
Helicity-induced shapes of resonant four-wave mixing responses from photofragments
Kouzov A, Radi P, Filippov N, Sinyakova T (2017), Helicity-induced shapes of resonant four-wave mixing responses from photofragments, in Journal of Physics: Conference Series, 810, 012019-012019.
Unraveling the electronic structure of transition metal dimers using resonant four-wave mixing
Visser B., Beck M., Bornhauser P., Knopp G., Gerber T., Abela R., van Bokhoven J. A., Radi P. P. (2016), Unraveling the electronic structure of transition metal dimers using resonant four-wave mixing, in JOURNAL OF RAMAN SPECTROSCOPY, 47(4), 425-431.
Perturbation-facilitated detection of the first quintet-quintet band in C 2
Bornhauser P., Marquardt R., Gourlaouen C., Knopp G., Beck M., Gerber T., van Bokhoven J. A., Radi P. P. (2015), Perturbation-facilitated detection of the first quintet-quintet band in C 2, in The Journal of Chemical Physics, 142(9), 094313-094313.

Collaboration

Group / person Country
Types of collaboration
Dr. D. Kozlov, General Physics Institute, Russian Academy of Sciences, Moscow Russia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Dr. A. Kouzov/St. Petersburg State University Russia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Dr. Roberto Marquardt/Université de Strasbourg France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Prof. U. Heiz, TU Munich Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Clustertreffen 2017 Talk given at a conference Disentangling the electronic structure of transition metal dimers by nonlinear optical spectroscopy 24.09.2017 Bacharach, Germany, Germany Beck Martin; Radi Peter;
SCS Fall Meeting 2017 Talk given at a conference Unraveling the electronic states of the copper dimer using nonlinear optical spectroscopy 21.08.2017 Bern, Switzerland Beck Martin; Radi Peter;
Gordon Research Conference - Clusters & Nanostructures Poster Disentangling the electronic structure of transition metal dimers by nonlinear optical spectroscopy 09.07.2017 South Hadley, MA, United States of America Beck Martin;
International Symposium on Molecular Spectroscopy 2017 Talk given at a conference RE-VISITING THE ELECTRONIC ENERGY MAP OF THE COPPER DIMER BY DOUBLE-RESONANT FOUR-WAVE MIXING 21.06.2017 Urbana-Champaign, United States of America Radi Peter;
ECONOS 2017 Talk given at a conference Unraveling the electronic states of the copper dimer using nonlinear optical spectroscopy 02.04.2017 Jena, Germany Beck Martin;
Seminarvortrag TU München Individual talk Electronic Structure of Diatomic Transition Metals by Double-Resonant Non-Linear Spectroscopy 28.11.2016 München, Germany Radi Peter;
SCS Fall Meeting 2016 Poster Unraveling the electronic states of transition metal species by optical spectroscopy 15.09.2016 Zürich, Switzerland Beck Martin;
ISSPIC XVIII, International Symposium on Small Particles and Inorganic Clusters Poster Unraveling the electronic states of transition metal species by optical spectroscopy 14.08.2016 Jyväskylä, Finland Beck Martin;
ECONOS 2016 Talk given at a conference Unravelling the complex electronic structure of transition metal dimers using four-wave mixing techniques 24.04.2016 Göteborg, Sweden Visser Bradley;
S3C 2016, Symposium on Size-Selected Clusters Talk given at a conference Towards double-resonance spectroscopy of small transition metal clusters: Rotational characterization of the A' state of Cu2 28.02.2016 Davos, Switzerland Radi Peter;
S3C 2016, Symposium on Size-Selected Clusters Poster Towards a stable laser ablation based metal cluster source for direct application of non- linear spectroscopy 28.02.2016 Davos, Switzerland Beck Martin;
Clustertreffen 2015 Talk given at a conference Mapping the electronic states of selected species within a mixed cluster beam by two-color resonant four-wave mixing spectroscopy 20.09.2015 Lindow, Germany Beck Martin;
SCS Fall Meeting 2015 Poster Mapping the electronic states of small transition metal clusters by nonlinear spectroscopy 04.09.2015 Lausanne, Switzerland Beck Martin;
GRC Clusters & Nanostructures 2015 Poster Two-color resonant four-wave mixing spectroscopy as a tool for mapping the electronic states of a selected species within a mixed cluster beam 05.07.2015 Girona, Spain Beck Martin;
International Symposium on Molecular Spectroscopy 2015 Talk given at a conference CHARACTERIZATION OF THE 1 5?u - 1 5?g BAND OF C2 BY TWO-COLOR RESONANT FOUR-WAVE MIXING AND LIF 26.06.2015 Champaign-Urbana, Illinois, United States of America Radi Peter;


Associated projects

Number Title Start Funding scheme
175490 Mapping the electronic structure of transition metal dimers by degenerate and two-color four-wave mixing 01.10.2017 Project funding (Div. I-III)
146387 Spectroscopic Characterization of Radicals by Degenerate and Two-Color Resonant Four-Wave Mixing 01.04.2013 Project funding (Div. I-III)

Abstract

Spectroscopic experiments are proposed to assess the electronic structure and chemical bonding of small heteronuclear molecules containing the transition metal atoms zinc, copper, palladium and platinum. The results from the investigation of such alloys will contribute significantly to the knowledge on the elementary catalytic reaction mechanisms. The catalytic activity is of these metals is governed by the high density of low lying electronic states of these atoms. These states interact in a complex manner to form metal-metal and metal-ligand bonds. Accordingly, a dense and complicated electronic structure is present and spectroscopic studies thereof are extremely challenging.In contrast to conventional spectroscopic methods that have been applied in the past to gas phase species of transition metals such as resonant two-photon ionization, laser-induced fluorescence and to a lesser extend cavity ring-down and intracavity laser absorption, we suggest to apply non-linear four-wave mixing. This method has been shown (i) to be sufficiently sensitive in the low density environment of a molecular beam, (ii) to be applicable to non-fluorescing molecules and molecules exhibiting a short lifetimes in the excited state and (iii) to provide the possiblity of optical-optical double-resonance investigations. The latter feature is a significant advantage for the investigation of dense and complex spectra that are typically encountered in the study of transition metal compounds.The generation of the heteronuclear transition metal species will be performed by using a laser-vaporization source, either consisting of a rod or disk target. Some of the alloy samples are commercially available as rod or disks. Other samples will be produced by sputtering sources available at our institute. Fs-ionization mass spectrometry will be applied to carefully optimize the source parameters and to produce an abundance of the targeted species which is sufficient for spectroscopic studies. Improved cluster sources are important owing to the quadratic dependence of the four-wave mixing signal on number density in the beam. In addition, such improved sources are required for future experiments at the free electron laser (XFEL) being built at the Paul Scherrer Institute and for experiments using synchrotron radiation at the Swiss light source (SLS). Initially, degenerate and two-color resonant four-wave mixing experiments on the copper dimer are planned. The Cu2 diatom is well characterized and suited to establish the potential of the method. The high selectivity owing to intermediate level labeling is advantageous to disentangle the complex rotational spectra obtained by resonant two-photon ionization and LIF. The method has the potential of observing computed low lying electronic levels of ? symmetry and to shed light on perturbations occurring in the ground state of the molecule. These important issues could not be clarified up to now with standard spectroscopic techniques. Investigations on heteronuclear dimers and clusters are planned subsequently that contain zinc, copper, palladium and platinum atoms. The proposal describes typical problems and challenges that are encountered in spectroscopic studies of homonuclear transition metals. It is outlined how the application of non-linear four-wave mixing is favorable in situations where more conventional methods fail.Heteronuclear dimers and small clusters are much less investigated. Few measurements are available which contain the targeted species. The coexistence of different transition metals yields interesting electronic, geometrical, chemical and catalytic properties. To support the spectroscopic experiments electronic structure calculations are indispensable. A close collaboration is planned with a theoretical group lead by Prof. Roberto Marquardt at the university of Strasbourg, France.
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