Work Group Prof. Dr. F. Temps

News

Jonas' and Ole's paper on pentafluoropyridine selected by JCP as 2017 Editor's Choice Article

Kiel, 28 February 2018:

Congratulations to Jonas and Ole for having their recent paper on pentafluoropyridine selected by the editors of JCP as 2017 Editor's Choice Article!

The article, co-authored by Jonas A. Kus, Ole Hüter and Friedrich Temps, with the title "Real-time observation of multi-mode vibronic coherence in pentafluoropyridine" was published in J. Chem. Phys. 47, 013938 (2017), DOI: 10.1063/1.4983306. As it is reported, Jonas and Ole discovered that out-of-plane vibrational motion of pentafluoropyridine creates strong multi-mode vibronic coupling between the first ππ* and πσ* excited electronic states. A resulting long-lived, pronounced electronic coherence of both states was experimentally observed using femtosecond mass spectrometry and photoelectron imaging spectroscopy. Oscillations with frequencies of 72 cm-1, 144 cm-1, 251 cm-1, and 281 cm-1 could be followed in time for more than 10 picoseconds.

Click here to see the list of the 2017 JCP Editor's Choice Articles, here to download the paper from the JCP website, or here to download the 2017 JCP Editor's Choice Articles booklet as pdf. 

  

Dennis Bank's and Hendrik Böhnke's poster presentations upgraded to talks at major conferences

Kiel, 24 July 2017:

Dennis Bank and Hendrik Böhnke both had their posters, which they had submitted for presentation at two important international symposia, unexpectedly upgraded to talks by the international organizing committees of the conferences! Dennis reported on his study of the "Ultrafast Photoisomerization Dynamics of Heterodiazocines upon S1(nπ*) Photoexcitation by Femtosecond Electronic Absorption Spectroscopy" at ICP2017, the 28th International Conference on Photochemistry in Strasbourg from 16 - 21 July 2017. Hendrik gave his talk entitled "Following the Ultrafast Dynamics of a Bistable Intramolecular H-Transfer Switch" at TRVS2017, the Time Resolved Vibrational Spectroscopy Meeting 2017 in Cambridge, UK, which also took place from 16 - 21 July 2017. More work, but more honor for both!  

Click to read Dennis' and Hendrik's abstracts.

   

Ole Hüter receives Familie Schindler Prize 2016

Kiel, 06 July 2017:

Congratulations to Dr. Ole Hüter for the 2016 Familie Schindler Prize for an outstanding Ph.D. Thesis in the field of Physical Chemistry!

Ole obtained his Ph.D. in our group in 2016 with a thesis on the "Femtochemistry of Vibronically Coupled Excited Electronic States of Carbonyl Compounds and Highly Fluorinated Benzene". During his work, he set up a highly versatile combined femtosecond time-of-flight mass spectrometer (fsTOF-MS) and photoelectron imaging (fsPEI) spectrometer for investigations of the ultrafast vibronic dynamics of electronically excited organic molecules in a pulsed supersonic molecular beam. He then used both techniques to study the photodissociation dynamics of acetone and other carbonyl compounds after excitation to the S1 (nπ*) state. He could show that the S1-excited molecules readily absorb another UV photon to reach high-lying Rydberg states, due to the huge absorption cross sections of those Rydberg states, and then quickly undergo dissociation. This process likely explains the alleged fast dissociation of acetone from the S1 state observed previously by Sergej Dziarzhytski by photofragment imaging in our group and in other laboratories. Ole also identified the origin of pronounced long-lived coherent dynamics of the TOF-MS and PEI signals of pentafluorobenzene (PFB). According to his results, the observed oscillations orginate from strong vibronic coupling of the optically bright ππ* state with the πσ* state at about 1 eV higher.

His work has already led to four valuable publications in J. Chem. Phys. and the like, with some more papers being on the way.

   

Sebastian Megow gave invited talk at DPG Spring Meeting

Mainz, 07 March 2017:  

Sebastian Megow's presentation at the DPG spring meeting 2017 in Mainz was upgraded by the organizers to an invited main talk due to the novelty and the huge interest in switching the spin state of transition metal complexes in solution at room temperature:

"Ultrafast dynamics of a magnetically bistable molecular switch by fs transient absorption spectroscopy"

Sebastian Megow*, Julia Bahrenburg*, Hendrik Böhnke*, Mats Bohnsack*, Mark Dittner*, Marcel Dommaschk**, Rainer Herges**, and Friedrich Temps* 
*Institute of Physical Chemistry and **Otto-Diels-Institute of Organic Chemistry, Christian-Albrechts-University Kiel 

 

Zwei Studenten und eine Tasse Kaffee
Photo-induced spin-state switching reactions of the azypridine Ni-porphyrin.   

  

The paper presented first results of our femtosecond studies of the photoreversible switching dynamics between the trans or low-spin configuration and the cis or high-spin configuration of an azopyridine-functionalized nickel-porphyrin, the so-called "Ni(II)-porphyrin record player" developed by our colleagues in the Otto Diels Institute of Organic Chemistry at CAU Kiel. The results show that the dynamics in both directions are determined by transitions between the Ni(d2) and Ni(d,d) excited states. A second highlight was the quantum yield determination for the switching from high-spin to low spin. 

Femtosecond spectroscopy at this level of complexity requires the collaboration of a large number of researchers with different expertise. This is reflected by the long list of co-authors. 

The abstract of the paper is accessible here in the DPG Verhandlungen. 

A second talk was given by Jonas Kus (co-authored by Jonas, Ole Hüter and Friedrich Temps), who reported on "Long-lived coherence with multiple vibrational frequencies in pentafluoropyridine as a probe of ππ*- πσ* vibronic coupling" (click here to read the abstract). 

  

XMP paper selected as Editor's Research Highlight in Focus on Chemistry

Kiel, 30 January 2017:

     molecules logo
       
 

We happily report that the chief editor of MDPI has selected our recent paper in Molecules, vol. 22, p. 160 (2017) by Katharina Röttger, Rebecca Stellmacher, Mayra C. Stuhldreier and Friedrich Temps on the

Ultrafast Electronic Deactivation Dynamics of Xanthosine Monophosphate

as Research Highlight in the January 30 edition of Focus on Chemistry.

Abstract: Ultrafast energy dissipation is a crucial factor for the photostability of DNA and RNA, but even some of the key electronic deactivation pathways in monomeric nucleic acid building stones are still controversial. Here, we report on the excited-state dynamics of the rare nucleotide xanthosine monophosphate as a function of deprotonation state (XMP vs. XMP ) and excitation wavelength ( λpump =  278–243 nm) by femtosecond time-resolved fluorescence and absorption spectroscopy. We show that the predominating relaxation channel leads to a return of the photo-excited molecules to the electronic ground state in τ ∼ 1 ps. The mechanism likely involves an out-of-plane deformation of the five-membered ring, different from the main electronic deactivation pathways in the canonical purine bases adenine and guanine. The results are discussed in terms of the structural and electronic differences of XMP compared to the canonical nucleotides.

To read the full article see: DOI 10.3390/molecules22010160 

  

Cover article on pyrimidine bases in Faraday Discussions on Ultrafast Imaging of Photochemical Dynamics

06 January 2017: 

   Faraday Discussion 194  
"Probing the excited state relaxation dynamics of pyrimidine nucleosides in chloroform solution"
  
Katharina Röttger, Hugo J. B. Marroux, Hendrik Böhnke,
David T. J. Morris, Angus T. Voice, Friedrich Temps, 
Gareth M. Roberts and Andrew J. Orr-Ewing
  
Faraday Discuss. 194, 683 - 708 (2016).
    

 

   
   
   
   
   
   
   
  
Abstract     Download PDF     View Full Size Image (59 KB)

  

JPC Letter on "Femtosecond Dynamics of Azobenzene on Gold Nanoparticles" hot of the press

09 March 2016: 

  

Femtosecond Time-Resolved Dynamics of trans-Azobenzene on Gold Nanoparticles

Anja Köhntopp, Mark Dittner and Friedrich Temps  

J. Phys. Chem. Lett. 7, 1088 - 1095 (2016),  DOI: 10.1021/acs.jpclett.6b00102
  
  

Azobenzene on Gold Nanoparticle

We report a first femtosecond time-resolved transient absorption study of the photoinduced ultrafast dynamics of trans-azobenzene (AB) on gold nanoparticles (AuNPs). The observed changes in optical density following excitation at λ = 357 nm were analyzed by using temperature-dependent Mie theory and by Lorentzian band fitting to disentangle the ultrafast relaxation of the local surface plasmon resonance (LSPR) excitation of the Au core and the electronic deactivation of the attached AB ligands. The analysis of the dynamics associated with the AB photochrome yielded lifetime constants of τ1 = 1.2 ± 0.2 ps and τ2 = 4.7 ± 1.1 ps. Both values together indicate surprisingly little difference in the dynamics of the AB ligand on the AuNPs vs in solution. Our results thus highlight the extraordinarily efficient electronic decoupling of the azo chromophore and the Au core by the alkyl linker chain.    

Link to JCPL Homepage    Download PDF    Download HTML    Supplementary Information  

  

New SFB 677 video podcast online: "Ultrafast Molecular Switches Caught in the Act"

Kiel, 15 December 2015:

Photochemically driven molecular switches are extremely fast: Typically, the switching process takes just 1 picosecond (10‑12 s). To understand the underlying molecular mechanisms, it is necessary therefore to investigate them on the time scale of femtoseconds (10‑15 s). Experimentally, this can be done with modern methods of ultrafast spectroscopy, as applied in our work group. In complementary work, the molecular switching dynamics is simulated theoretically in the group of Professor Bernd Hartke. A new video podcast by the Kiel CRC 677 "Function by Switching" illustrates our approach:  

  

SFB video podcast
Click on image to start the video in a new page.
 

 

In combined studies of this kind within CRC 677, the photochemical mechanisms of basic switches like azobenzenes and furylfulgides have been analyzed in high details. This, in turn, allows us to systematically improve these molecules, i.e. to develop molecular systems that can be switched from one state to the other more selectively, more rapidly, more efficiently and more robustly. These achievements directly translate to improved applications of the switches, for example in functional materials or as tiny actuators and motors in molecular machines. The video podcast illustrates one of our improvements: An additional bridge between the two phenyl rings of azobenzene improves its switching properties dramatically, by shortening the molecular pathways from one state to the other, and by eliminating other molecular movements that would reduce the switching efficiency. Additionally, the bridge separates the excitation light wavelengths for the forward and backward switching directions. 

  

Friedrich Temps receives Wilhelm Jost Medal

Göttingen, 10 December 2015:

       F. Wilhelm Jost
F. Wilhelm Jost

Friedrich Temps received the Wilhelm Jost Medal of the Academy of Sciences Göttingen for the 2015 Wilhelm Jost Memorial Lecture

"Ultrafast Light-Induced Transformations in Molecular Switches and DNA Building Blocks"   

The Wilhelm Jost Memorial Lecture and Medal is awarded by the Academy of Sciences Göttingen and jointly by the Deutsche Bunsengesellschaft für Physikalische Chemie to commemorate the many scientific achievements and merits of F. Wilhelm Jost (1903 - 1968). The Lecture is traditionally given at the former work places of W. Jost, in Halle, Berlin, Hannover, Leipzig, Marburg, Darmstadt and Göttingen. The medal is presented after the last lecture in Göttingen.

Links to lecture scheduleAcademy of Sciences Göttingenlist of previous Jost lecturerslarger photo of Jost Medal.

  

CAU awards Germany scholarships

Kiel, 28 October 2015:  

CAU president Prof. Lutz Kipp and vice-president Prof. Ilka Parchmann announced the winners of the 2015/16 Germany Scholarships (Deutschlandstipendium) at Christian-Albrechts-University in a festive ceremony at the Science Center. This year marks the third in which we contributed with funding for a one-year stipend, open to all academic disciplines in the tradition of CAU as "universitas".  

 

Germany Scholarships 2015 Group Photo
Photo: Christina Kloodt  

  

"Affording their studies has become very difficult for many students in recent years, as little if any time remains since the conversion to the Bachelor/Master system for financing their living expenses by working besides their studies during the semester or in the semester breaks. A Germany Scholarship is not only a help, but also a special recognition and motivation. We are extraordinarily glad to be able to support and honor our best, most committed and engaged young talent at CAU in this way."

The Germany Scholarship provides financial and non-material support to high-achieving and committed students at German universities from all over the world. Businesses, foundations and private individuals sponsor young talent with a pledge of 50 % of the cost of a stipend per year. The Federal Government matches each donation with the other 50 %. 

Click here to view the above photograph in larger format, click here for the official CAU press release.

  

Cover article on G∙C base pair in Angew. Chem. hot of the press

13 October 2015: 

AngewChem_Cover_GC_small.jpg  
"Ultraviolet Absorption Induces Hydrogen-Atom Transfer in G∙C Watson-Crick" DNA Base Pairs in Solution"
  
Katharina Röttger, Hugo J. B. Marroux, Michael P. Grubb,
Philip M. Coulter, Hendrik Böhnke, Alexander S. Henderson,
M. Carmen Galan, Friedrich Temps, Andrew J. Orr-Ewing
and Gareth M. Roberts
  
Angew. Chem. Int. Ed. 54, 14719 - 14712 (2015).
    

G-C

 
  
Abstract     Download PDF     Supplementary Information     Enlarged Cover     CAU Press Release
  

  

Wilhelm Jost Memorial Lecture 2015 to be given by Prof. F. Temps

Göttingen and Kiel, 01 July 2015:

The 2015 Wilhelm Jost Memorial Lecture sponsored by the Academy of Sciences Göttingen on proposition by the Deutsche Bunsengesellschaft für Physikalische Chemie is traditionally given at the former work places of W. Jost and additional institutions to commemorate his many achievements and merits.  

The title of the 2015 Wilhelm Jost Lecture to be given by F. Temps is

"Ultrafast Light-Induced Transformations in Molecular Switches and DNA Building Blocks"  

 

Lecture Calendar:

Date University          Date University
18.11.2015 Martin Luther University Halle    19.11.2015  University of Leipzig 
25.11.2015  Technical University Darmstadt    01.12.2015 Technical University Kaiserslautern 
02.12.2015  Philipps University Marburg    03.12.2015  Leibniz University Hannover 
09.12.2015  Humboldt University Berlin    10.12.2015  Georg August University Göttingen* 
*lecture with modified title 

    

Link to the Academy of Sciences Göttingen, and link to the list of previous Wilhelm Jost Lecturers.

 

SFB 677 "Function by Switching" funded for third period

Kiel, 22 May 2015:

sfb_logo        

The German Research Foundation (DFG) has announced that it will continue to fund the Collaborative Research Centre (Sonderforschungsbereich) 677 "Function by Switching" at CAU Kiel for a third period until 2019 with another 8.9 million EUR. In one continuing (A1) and one new project (A7) in our group, we investigate the dynamics of molecular switches in solution and in functional photoresponsive environments and systems (e.g. polymer colloids, polymer films and monolayers on quartz surfaces and on nanoparticles). To achive our ambitious goals, we use state-of-the-art femto- and picosecond time-resolved optical spectroscopies (e.g. broadband femtosecond transient absorption, fs fluorescence up-conversion and fs broadband fluorescence) in the VIS and UV regions between 220 - 800 nm. In addition, we recently complemented our ultrafast instrumentation for the third CRC funding period by a new femtosecond UV pump / IR probe spectrometer allowing for detection in the IR between 900 - 3900 cm-1

The CRC encompasses 16 scientific sub-projects, one Public Outreach project and an integrated Graduate Research Training Group. Work groups from the Chemistry, Physics, and Materials Science departments at CAU Kiel collaborate closely to develop and investigate tiny light-driven molecular switches for realizing new functions and functional materials. The CRC has been established in 2007. The speaker is Prof. Rainer Herges of the Otto Diels Institute of Organic Chemistry. 

Our continuing project A1 is led jointly by Prof. Bernd Hartke, Dr. Falk Renth, and Prof. Temps, our new project A07 is led jointly by Prof. TempsProf. Ulrich Lüning, and Prof. Bernd Hartke

Please contact us for questions and ask for available Ph.D. and Master/Diploma Thesis projects.

Click here for the CAU press release.

Click here for the SFB 677 homepage.

Click here for more information on project A1: "Ultrafast Dynamics of Photo-induced Switching Processes".

Click here for more information on project A7: "Dynamics of H-Transfer Switches".

   

Chemical Communication hot of the press (published on the web 15 July 2014)

15 July 2014: 

  

Photoisomerisation and Ligand-Controlled Reversible Aggregation of Azobenzene-Functionalised Gold Nanoparticles

Anja Köhntopp, Alexandra Dabrowski, Michal Malicki and Friedrich Temps  

Chem. Commun. 50, 10105 - 10107 (2014),  DOI: 10.1039/C4CC02250E 
  

AuNP

  

The photochemical behaviour of functionalised gold nanoparticles (AuNPs) carrying azobenzenethiolate–alkylthiolate monolayers was investigated. Repeated transcis andcistrans isomerisation cycles could be performed in all cases with high efficiency. Reversible photoinduced aggregation was observed when azothiolates with long alkyl spacers (≥C7) were combined with short (C5) alkylthiolate coligands. The choice of a coligand thus offers control over the aggregation properties of the nanoparticles.

Abstract on ChemComm Homepage    Download PDF    Supplementary Information (1219K)