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Spektroskopie, Photophysik und Photochemie von Molekülclustern in Überschallmolekularstrahlen

English title Spectroscopy, photophysics and photochemistry of molecular clusters in supersonic beams
Applicant Leutwyler Samuel
Number 152816
Funding scheme Project funding (Div. I-III)
Research institution Departement für Chemie, Biochemie und Pharmazie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Physical Chemistry
Start/End 01.04.2014 - 31.03.2017
Approved amount 452'892.00
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Keywords (10)

nucleobase dimers; intermolecular interactions; pi-stacking; laser spectroscopy; molecular beams; proton transfer; molecular excitons; hydrogen-bond; nucleobases; H-atom transfer

Lay Summary (German)

Lead
Im Rahmen dieses SNF-Projekts untersuchen wir die Eigenschaften von isolierten und sehr kalten Molekülen, Moleküldimeren und Molekülclustern in der Gasphase. In vier Unterprojekten beschäftigen wir uns mit den Themen: (A) Photophysik und Photochemie von isolierten und kalten Nukleobasen, insbesondere Adenin und Cytosin sowie ihren chemischen Derivaten, (B) Photophysik von Molekülkomplexen zwischen elektronen-reichen Donoren und elektronenarmen Akzeptor-Molekülen (sog. Donor-Akzeptor-Komplexe), (C) dem ultraschnellen Austausch elektronischer Energie zwischen zwei Molekülen in Paarkomplexen, (D) dem lichtinduzierten Protonentransfer von einem lichtaktivierbaren Molekül auf die umgebende Lösungsmittelhülle.
Lay summary

Die Verwendung von Ueberschall-Molekularstrahlen erlaubt es, Moleküle zu verdampfen, im Molekularstrahl zu isolieren und anschliessend auf tiefe Temperaturen (T=2-5 Kelvin) in ihren tiefsten quantenmechanischen Zustand
abzukühlen. Wir regen die Moleküle dann mit abstimmbaren und spektral hoch auflösenden Lasern rotatorisch, vibratorisch oder elektronisch an und ionisieren sie anschliessend mit einem zweiten Photon. Die erzeugten Ionen werden massenspektrometrisch getrennt und mit hoher Empfindlichkeit nachgewiesen. Die Kombination dieser drei Techniken erlaubt es Einzelmoleküle, Moleküldimere bzw. Molekülcluster detailliert zu untersuchen.

Im Projekt (A) wird die Photophysik und Photochemie von isolierten Nukleobasen untersucht. Nukleobasen codieren die genetischen Information in der DNS bzw. RNS sämtlicher Organismen. Von den fünf wichtigen Nukleobasen untersuchen wir vor allem Adenin und Cytosin, insbesondere ihre Geometrien, Vibrationen, Lebensdauern sowie ihre radiativen und nicht-radiativen Prozesse. Wir konnten zeigen, dass isolierte Adenin- wie Cytosinderivate in der Gasphase nach Lichtanregung mit 50-80% Ausbeute in einen chemisch hochreaktiven Triplettzustand (T1) übergehen. Dieses Verhalten steht im kompletten Gegensatz zum bisher beobachteten Verhalten in wässriger Lösung, wo >99% der Moleküle nach Lichtanregung in den elektronischen Grundzustand (S0) zurückkehren.

In den Projekten B und C werden zwischenmolekulare Kräfte untersucht, die Moleküle zu Paaren und zu grösseren Clustern zusammenhalten. Diese sind (1) Wasserstoffbrücken zwischen Nukleobasen, (2) Wasserstoffbrücken zwischen Nukleobase und einzelnen/ mehreren Wassermolekülen (Solvatcluster), und (3) sog. pi-Stapel-Interaktionen zwischen zwei Nukleobasen, wie sie in der DNS-Doppelhelix auftreten. In Projekt (C) werden Energietransfers in Molekülpaaren untersucht, in Projekt (D) Protonentransfers zwischen einem Einzelmolekül und seiner Lösungsmittelumgebung.

Direct link to Lay Summary Last update: 29.04.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Transition from Water Wires to Bifurcated H-Bond Networks in 2-Pyridone·(H 2 O) n , n = 1–4 Clusters
Siffert Luca, Blaser Susan, Ottiger Philipp, Leutwyler Samuel (2018), Transition from Water Wires to Bifurcated H-Bond Networks in 2-Pyridone·(H 2 O) n , n = 1–4 Clusters, in The Journal of Physical Chemistry A, 122(48), 9285-9297.
Planarizing cytosine: The S1 state structure, vibrations, and nonradiative dynamics of jet-cooled 5,6-trimethylenecytosine
Trachsel Maria A., Lobsiger Simon, Schär Tobias, Blancafort Lluis, Leutwyler Samuel (2017), Planarizing cytosine: The S1 state structure, vibrations, and nonradiative dynamics of jet-cooled 5,6-trimethylenecytosine, in J. Chem. Phys., 146(24), 244308-1-244308-13.
Excitonic Splitting and Vibronic Coupling Analysis of the m -Cyanophenol Dimer
Balmer Franziska A., Kopec Sabine, Köppel Horst, Leutwyler Samuel (2017), Excitonic Splitting and Vibronic Coupling Analysis of the m -Cyanophenol Dimer, in The Journal of Physical Chemistry A, 121(1), 73-87.
The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine
Trachsel Maria A., Wiedmer Timo, Blaser Susan, Frey Hans-Martin, Li Quansong, Ruiz-Barragan Sergi, Blancafort Lluis, Leutwyler Samuel (2016), The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine, in J. Chem. Phys., 145(13), 134307-1-134307-15.
The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine
Trachsel Maria A., Wiedmer Timo, Blaser Susan, Frey Hans-Martin, Li Quansong, Ruiz-Barragan Sergi, Blancafort Lluís, Leutwyler Samuel (2016), The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine, in The Journal of Chemical Physics, 145(13), 134307-134307.
Experimental and Theoretical Determination of Dissociation Energies of Dispersion-Dominated Aromatic Molecular Complexes
Frey Jann, Holzer Christoph, Klopper Willem, Leutwyler Samuel (2016), Experimental and Theoretical Determination of Dissociation Energies of Dispersion-Dominated Aromatic Molecular Complexes, in Chem. Rev., 116(9), 5614-5641.
Do Hydrogen Bonds Influence Excitonic Splittings?
Balmer Franziska A., Ottiger Philipp, Leutwyler Samuel (2016), Do Hydrogen Bonds Influence Excitonic Splittings?, in CHIMIA International Journal for Chemistry, 70(4), 284-287.
Gas-Phase Cytosine and Cytosine-N 1 -Derivatives Have 0.1–1 ns Lifetimes Near the S 1 State Minimum
Blaser Susan, Trachsel Maria A., Lobsiger Simon, Wiedmer Timo, Frey Hans-Martin, Leutwyler Samuel (2016), Gas-Phase Cytosine and Cytosine-N 1 -Derivatives Have 0.1–1 ns Lifetimes Near the S 1 State Minimum, in The Journal of Physical Chemistry Letters, 7(5), 752-757.
Intersystem crossing rates of S1 state keto-amino cytosine at low excess energy
Lobsiger Simon, Etinski Mihajlo, Blaser Susan, Frey Hans-Martin, Marian Christel, Leutwyler Samuel (2015), Intersystem crossing rates of S1 state keto-amino cytosine at low excess energy, in The Journal of Chemical Physics, 143(23), 234301-234301.
Experimental and Calculated Spectra of π-Stacked Mild Charge-Transfer Complexes: Jet-Cooled Perylene·(Tetrachloroethene) n , n = 1,2
Balmer Franziska A., Ottiger Philipp, Leutwyler Samuel (2015), Experimental and Calculated Spectra of π-Stacked Mild Charge-Transfer Complexes: Jet-Cooled Perylene·(Tetrachloroethene) n , n = 1,2, in The Journal of Physical Chemistry A, 119(42), 10462-10474.
Modeling the Histidine–Phenylalanine Interaction: The NH···π Hydrogen Bond of Imidazole·Benzene
Trachsel Maria A., Ottiger Philipp, Frey Hans-Martin, Pfaffen Chantal, Bihlmeier Angela, Klopper Wim, Leutwyler Samuel (2015), Modeling the Histidine–Phenylalanine Interaction: The NH···π Hydrogen Bond of Imidazole·Benzene, in The Journal of Physical Chemistry B, 119(25), 7778-7790.
The elusive S2 state, the S1 / S2 splitting, and the excimer states of the benzene dimer
Balmer Franziska A., Trachsel Maria A., van der Avoird Ad, Leutwyler Samuel (2015), The elusive S2 state, the S1 / S2 splitting, and the excimer states of the benzene dimer, in The Journal of Chemical Physics, 142(23), 234306-234306.
Analysis of the S2 ← S0 vibronic spectrum of the ortho -cyanophenol dimer using a multimode vibronic coupling approach
Kopec Sabine, Ottiger Philipp, Leutwyler Samuel, Köppel Horst (2015), Analysis of the S2 ← S0 vibronic spectrum of the ortho -cyanophenol dimer using a multimode vibronic coupling approach, in The Journal of Chemical Physics, 142(8), 084308-084308.
Excitonic splittings in molecular dimers: why static ab initio calculations cannot match them
Ottiger Philipp, Köppel Horst, Leutwyler Samuel (2015), Excitonic splittings in molecular dimers: why static ab initio calculations cannot match them, in Chem. Sci., 6(11), 6059-6068.
Excitonic Splitting, Delocalization, and Vibronic Quenching in the Benzonitrile Dimer
Balmer Franziska A., Ottiger Philipp, Leutwyler Samuel (2014), Excitonic Splitting, Delocalization, and Vibronic Quenching in the Benzonitrile Dimer, in The Journal of Physical Chemistry A, 118(47), 11253-11261.
Switching on the fluorescence of 2-aminopurine by site-selective microhydration
Lobsiger Simon, Blaser Susan, Sinha Rajeev K., Frey Hans-Martin, Leutwyler Samuel (2014), Switching on the fluorescence of 2-aminopurine by site-selective microhydration, in Nature Chemistry, 6(11), 989-993.
Accurate computations of the structures and binding energies of the imidazole ⋯ benzene and pyrrole ⋯ benzene complexes
Ahnen Sandra, Hehn Anna-Sophia, Vogiatzis Konstantinos D., Trachsel Maria A., Leutwyler Samuel, Klopper Wim (2014), Accurate computations of the structures and binding energies of the imidazole ⋯ benzene and pyrrole ⋯ benzene complexes, in Chemical Physics, 441, 17-22.
Gas-phase Lifetimes of Nucleobase Analogues by Picosecond Pumpionization and Streak Techniques
Blaser Susan, Frey Hans-Martin, Heid Cornelia G., Leutwyler Samuel (2014), Gas-phase Lifetimes of Nucleobase Analogues by Picosecond Pumpionization and Streak Techniques, in CHIMIA International Journal for Chemistry, 68(4), 260-263.
Excited-State Structure, Vibrations, and Nonradiative Relaxation of Jet-Cooled 5-Fluorocytosine
Lobsiger Simon, Trachsel Maria A., Den Takuya, Leutwyler Samuel (2014), Excited-State Structure, Vibrations, and Nonradiative Relaxation of Jet-Cooled 5-Fluorocytosine, in The Journal of Physical Chemistry B, 118(11), 2973-2984.
Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine
Trachsel Maria A., Lobsiger Simon, Schär Tobias, Leutwyler Samuel (2014), Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine, in The Journal of Chemical Physics, 140(4), 044331-044331.
Watson–Crick and Sugar-Edge Base Pairing of Cytosine in the Gas Phase: UV and Infrared Spectra of Cytosine·2-Pyridone
Frey Jann A., Ottiger Philipp, Leutwyler Samuel (2014), Watson–Crick and Sugar-Edge Base Pairing of Cytosine in the Gas Phase: UV and Infrared Spectra of Cytosine·2-Pyridone, in The Journal of Physical Chemistry B, 118(3), 682-691.

Collaboration

Group / person Country
Types of collaboration
Prof. Wim Klopper, Universität Karlsruhe Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Dr. Colin Western, University of Bristol Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Horst Koeppel, Universität Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Prof. Lluis Blancafort, University of Girona Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Tomasz A. Wesolowski (MeR) Switzerland (Europe)
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
C4 Workshop: «Computational quantum chemistry: Quo vadis ?» Talk given at a conference Connecting Experiment and Theory: “Marriage has Many Pains, but Celibacy has no Pleasures” 08.06.2017 ETH Zürich, Switzerland Leutwyler Samuel;
Robert-Bunsen Gedenkvorlesung der Deutschen Bunsengesellschaft Individual talk Excitonic Splittings in Molecular Dimers (and why ab Initio Calculations Cannot Match Them) 30.01.2017 Berlin, Germany Leutwyler Samuel;
Seminar Institut für Physikalische Chemie, Universität Düsseldorf Individual talk The Photophysics of Cold Excited-State Cytosines 09.01.2017 Universität Duisburg, Germany Leutwyler Samuel;
Seminar am Center for Free-Electron Lasers/ DESY Individual talk The Photophysics of Cold Excited-State Cytosines 24.10.2016 CFEL/DESY, Universität Hamburg, Germany Leutwyler Samuel;
20th Symposium on Atomic, Cluster and Surface Physics (SASP) 2016 Talk given at a conference A Reductionist View of the Photophysics of Excited-State Cytidine 07.02.2016 Davos, Switzerland Frey Hans-Martin; Lobsiger Simon; Trachsel Maria; Leutwyler Samuel;
SPP1807 Workshop "Control of London Dispersion Interactions in Molecular Chemistry" Universität Göttingen Poster Charge-Transfer Contribution to the Binding Energies of Disperisvel Bound Complexes 19.10.2015 Universität Göttingen, Germany Feraud Géraldine; Leutwyler Samuel; Balmer Franziska;
Fall Meeting of the Swiss Chemical Society 2015 Poster UV Spectra and Nonradiative Relaxation Dynamics of Jet-Cooled N1-Substituted Cytosines 04.09.2015 EPFL Lausanne, Switzerland Leutwyler Samuel; Trachsel Maria;
Fall Meeting of the Swiss Chemical Society 2015 Talk given at a conference (Benzonitrile)2 and meta-(Cyanophenol)2: Influence of a Hydroxy Group on the Excitonic Splitting 04.09.2015 EPF Lausanne, Switzerland Balmer Franziska;
QAMTS XVI International Workshop 2015 Talk given at a conference Competing Excitonic Energy Transfer and Double Proton Transfer in the 7-Azaindole Dimer 31.05.2015 Beatenberg, Switzerland Leutwyler Samuel;
Electronic Properties of pi-Conjugated Materials III, Graduiertenkolleg GRK 1221, Universität Würzburg Poster Weak and Strong Perylene Charge-Transfer Complexes: Jet-Cooled Spectra and Computational Investigations 10.03.2015 Universität Würzburg, Germany Leutwyler Samuel; Balmer Franziska;
Electronic Properties of pi-Conjugated Materials III, Graduiertenkolleg GRK 1221, Universität Würzburg Talk given at a conference Weak and Strong Perylene Charge-Transfer Complexes: Jet-Cooled Spectra and Computational Investigations 10.03.2015 Universität Würzburg, Germany Leutwyler Samuel; Balmer Franziska;
Isolated Biomolecules and Biomolecular Interactions (IBBI) 2014 Poster Supersonic Jet Spectra and Nonradiative Relaxation of Methylated Cytosines 18.05.2014 Porquerolles, France Leutwyler Samuel; Lobsiger Simon; Trachsel Maria;
2014 Gordon Research Conference on Molecular and Ionic Clusters Poster (Benzene)2 and (Benzonitrile)2: Excitonic and Site Effects on the S1/S2 Splitting 27.04.2014 Lucca, Italy Balmer Franziska; Trachsel Maria; Ottiger Philipp; Leutwyler Samuel;


Awards

Title Year
Robert-Bunsen-Vorlesung 2015

Associated projects

Number Title Start Funding scheme
132540 Spektroskopie, Photophysik und Photochemie von Molekülclustern in Überschallmolekularstrahlen 01.10.2010 Project funding (Div. I-III)
144490 Ultraschnelle nichtlineare Raman-Messungen von Molekülen und Clustern 01.10.2012 Project funding (Div. I-III)

Abstract

Scientific goals:Project A: Experimental and theoretical investigations of supersonicallycooled nucleobases, nucleobase analogues and dimers of these. Determination of ground- and excited state rotational constants and geometries, vibrational and vibronic spectra, lifetimes, radiative and nonradiative pathways in the excited state. These will allow to understand the respective properties of the related nonfluorescent canonical nucleobases. The investigations of nucleobase base pairs will address the H-bonded topologies (Watson-Crick, reversed Watson-Crick, Wobble, Hoogsteen, sugar-edge), as well the hydrogen-bond vibrations and binding energies. Analogous investigations will also be undertaken on nanohydrated jet-cooled nucleobase analogues.Project B: Spectroscopy of T-shaped and pi-stacked aromatic dimers. Foraromatics that lack hydrogen-bonding groups, the energetic competition between T-shaped or ''herringbone'' arrangements and co-planar pi- stacking is a recurring theme in crystallography, materials chemistry and biochemistry. We propose systematic experimental and theoretical investigations of supersonically cooled T-shaped or pi-stacked aromatic dimers.Project C: Spectroscopic and theoretical investigations of symmetric homodimers. The theory of excitonic interactions in molecular dimers (with extensions to vibronic coupling) have been developed on the 1960s. So far, these theories and calculations have remained poorly tested by experiment. Our recent work on centrosymmetric hydrogen-bonded homodimers has shown the existing exciton/vibronic coupling theories must be extended to include (i) coupling to intermolecular vibrations, (ii) multimode vibronic coupling and (iii) vibronic quenching effects.Project D: Experimental and theoretical investigations of proton and H-atomtransfer reactions in supersonically cooled clusters, employing laser-triggered photoacids and hydrogen-bonding solvents. Investigation of proton and H-atom translocation along H-bonded solvent "wires". Determination of the temporal dependence and mechanisms of transfers using laser spectroscopic techniques, laser pico- and femtosecond kinetic methods and ab initio theoretical methods.
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