MBI Staff member
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Dr. Andrea Lübcke

luebcke [at] mbi-berlin.de

+49 30 6392 1318

Scientist

Member of Projects: (currently) 2.1 "Laser Plasma Dynamics and Particle Acceleration"

(from Jan. 2017): 3.1 "Dynamics of Condensed Phase Molecular Systems"

 

Research Topic


Short introduction:


My main scientific interest is in the ultrafast molecular dynamics in solution which will return into the focus of my research in 2017. However, to bridge a project gap I spent the last months on laser plasma dynamics and ion acceleration - a topic that I dealt already with during my PhD studies in Jena.

Regarding ultrafast molecular dynamics, I investigate how a molecule evolves after absorption of a photon. Thus, the basic idea is to watch a molecule during photophysical or photochemical reaction. In particular, I am interested in the photophysics of DNA. DNA safely stores our genetic code. "Safely" is the keyword in the previous sentence - because DNA is surprisingly photostable - which is obviously a prerequisit for the development of life on earth. The mechanism behind this photostability is still not understood. There are different routes to approach this problem: from studying the photoresponse of the individual building blocks in vacuum to the investigation of living cells. Here, we use the bottom-up principle, i. e. we start from the small individual building blocks and slowly increase the complexity of the system. In addition, we study these system in aqueous environment. The method of choice is time-resolved photoelectron spectroscopy in solution. This technique in principle allows us to follow the molecular dynamics in energy and time, and to identify all transient states involved.

With the start of the new project in January 2017, a position for a PhD student is available (will be advertised shortly on the carreer website of MBI). I also offer topics for Bachelor and Master works. In case of interest, please contact me. I am looking forward to hearing from you.

 



Curriculum vitae


  • 05/2015 - present: Scientist at Max-Born-Institute
    • Development of a superresolution camera for the soft x-ray regime in collaboration with a medium-sized enterprise
    • Laser-plasma physics, laser particle acceleration
  • 12/2014 - 05/2015 guest scientist at Max-Born-Instiute
    • Time-resolved photoelectron spectroscopy of liquid samples
    • Eexcited state dynamics of biomolecules in solution
  • 10/2014 - 01/2015 Teacher
  • 03/2014-10/2014 Scientist at Max-Born-Institute
    • Time-resolved photoelectron spectroscopy of liquid samples
    • Excited state dynamics of biomolecules in solution
  • 03/2013 - 02/2014 Scientist at EPF Lausanne (Switzerland)
    • Time-resolved X-ray absorption spectroscopy, X-ray scattering and X-ray diffraction
    • Femtoslicing
  • 05/2008 - 02/2013 Scientist at Max-Born-Institut
    • Time-resolved photoelectron spectroscopy of liquid samples
    • Excited state dynamics of biomolecules in solution
  • 10/2007 - 01/2008 PostDoc at Freie Universität (FU) Berlin
  • 10/2002 - 10/2007 PhD student at Friedrich-Schiller Universität Jena
    • Time-resolved x-ray diffraction
    • Laser-plasma interaction
    • X-ray emission spectroscopy
    • Dissertation: Time-resolved X-ray diffraction on superconducting YBa2Cu3O7 epitaxially grown on SrTiO3
  • 10/1997 - 09/2002 Studies of physics (Diplom) at Friedrich-Schiller Universität Jena
    • Diploma work: "Exploitation of the Borrmann effect for the development of an ultrafast x-ray switch"

 

Research Highlights


New Insights into the photophysics of the DNA base thymine

(11th February 2015)

DNA stores our genetic code. Solar UV radiation has sufficiently high energy to basically break bonds of the DNA and thus cause DNA damage. Although DNA (e. g. in our skin cells) is exposed to intense UV light irradiation, DNA proves to be surprising photostable. It is well established that this is due to efficient mechanisms that convert electronic energy into other forms of energy, in particular heat. An important role is played by so-called conical intersections between electronic excited potential energy surfaces and the ground state potential energy surface. These conical intersections are associated with structural changes of the molecules. The exact pathways back into the electronic ground state however are topic of intense research.

Although DNA is a macro molecule with billions of atoms (in case of human DNA), it can still be divided into only a few structural (and functional) elements: four DNA bases, a sugar moiety and a phosphate group. The absorption of UV light exclusively takes place in the DNA bases. For this reason it is a common scientific approach to investigate the UV response of DNA bases, first.

A team of scientists from MBI and universities of Hokkaido and Hirosaki in Japan have for the first time investigated the DNA base thymine in aqueous solution by time-resolved photoelectron spectroscopy and questioned existing ideas about the excited-state relaxation process in this base. So far was supposed that a significant fraction of the excited-state population remains in a dark nπ* state instead of immediately returning to the ground state via a conical intersection. This dark state cannot be observed by optical spectroscopy (e. g. transient absorption or fluorescence upconversion), directly. Corresponding limitations however do not exist for photoelectron spectroscopy.

By combining experiment and simulation, for the first time two different relaxation pathways were identified. Both pathes evolve in the first excited state (ππ*). The faster reaction path is associated with a twist of the aromatic ring and leads to repopulation of the electronic ground state within 100 fs. The second path involves an out-of-plane motion of the carbonyl group, and the molecule returns to the ground state within 400 fs. The scientists did not find any indication for an important role of the second excited nπ* state and conclude that this state is not involved in the relaxation process.

Original publication:
Franziska Buchner, Akira Nakayama, Shohei Yamazaki, Hans-Hermann Ritze, Andrea Lübcke
Excited-State relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation, JACS,
JACS, DOI: 10.1021/ja511108u

Fig. 1: After UV excitation thymine evolves on the (ππ*) excited state surface along two different reaction coordinates. The first involves a twisting of the aromatic ring, the second an out-of-plane motion of the carbonyl group. In contrast to existing ideas, the nπ* state does not seem to be involved in the relaxation process..

 


Publications

Publications at MBI

List of own publications with no relation to MBI:

  • X-ray study of femtosecond structural dynamics in the 2D charge density wave compound 1T-TaS2
    C. Laulhè, L. Cario, B. Corraze, E. Janod, T. Huber, G. Lantz, S. Boulfaat, A. Ferrer, S. O. Mariager, J. A. Johnson, S. Grübel, A. Lübcke, G. Ingold, P. Beaud, S. L. Johnson, S. Ravy
    Physica B: Cond. Matter 460, 100 (2015)

  • Coherent structural dynamics of a prototypical charge-density-wave-to-metal transition
    T. Huber, S. O. Mariager, A. Ferrer, H. Schaefer, J. A. Johnson, S. Gruebel, A. Lübcke, L. Huber, T. Kubacka, C. Dornes, C. Laulhé, S. Ravy, G. Ingold, P. Beaud, J. Demsar, S. L. Johnson
    Phys. Rev. Lett. 113, 026401 (2014)

  • Time-resolved X-ray Diffraction of Cryogenic Samples Using a Laser Based Plasma Source
    R. Loetzsch, A. Lübcke, F. Zamponi, T. Kämpfer, I. Uschmann, E. Förster
    in "Short Wavelength Laboratory Sources" p. 398 (2014)

  • Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy
    F. Zamponi, T. J. Penfold, M. Nachtegaal, A. Lübcke, J. Rittmann, C. J. Milne, M. Chergui, J. A. Van Bokhoven
    Phys. Chem. Chem. Phys. 16, 23157 (2014)

  • Laser-accelerated ions from layered targets
    L. A. Gizzi, S. Betti, E. Förster, A. Giulietti, T. Kämpfer, P. Köster, L. Labate, T. Levato, A. Lübcke, A. P. L. Robinson, I. Uschmann, F. Zamponi
    Nucl. Instr. Meth. Phys. Res. Sec. A 620, 83 (2010)

  • The cubic to tetragonal phase transition in SrTiO3 single crystals near its surface under internal and external strains
    R. Loetzsch, A. Lübcke, I. Uschmann, E. Förster, V. Große, M. Thuerk, T. Koettig, F. Schmidl, P. Seidel
    Appl. Phys. Lett. 96, 1901 (2010)

  • Experimental investigation of fast electron transport in solid density matter: Recent results from a new technique of X-ray energy-encoded 2D imaging
    L. Labate, E. Förster, A. Giulietti, D. Giulietti, S. Höfer, T. Kämpfer, P. Köster, M. Kozlova, T. Levato, R. Lötzsch, A. Lübcke, T. Mocek, J. Polan, B. Rus, I. Uschmann, F. Zamponi, L. A. Gizzi
    Laser and Part. Beams 27, 643 (2009)

  • Observation of electron transport dynamics in high intensity laser interactions using multi-energy monochromatic x-ray imaging
    L. A. Gizzi, A. Giulietti, D. Giulietti, P. Köster, L. Labate, T. Levato, F. Zamponi, A. Lübcke, T. Kämpfer, I. Uschmann, E. Förster, A. Antonicci, D. Batani
    Plasma Phys. and Control. Fusion 49, B211 (2007)

  • Novel x-ray multispectral imaging of ultraintense laser plasmas by a single-photon charge coupled device based pinhole camera
    L. Labate, A. Giulietti, D. Giulietti, P. Köster, T. Levato, L. A. Gizzi, F. Zamponi, A. Lübcke, T. Kämpfer, I. Uschmann, E. Förster
    Rev. Sci. Instr. 78, 103506 (2007)

  • Novel method for characterizing relativistic electron beams in a harsh laser-plasma environment
    B. Hidding, G. Pretzler, M. Clever, F. Brandl, F. Zamponi, A. Lübcke, T. Kämpfer, I. Uschmann, E. Förster, U. Schramm, R. Sauerbrey, E. Kroupp, L. Veisz, K. Schmid, S. Benavides, S. Karsch
    Rev. Sci. Instr. 78, 083301 (2007)

  • X-ray polarization-dependent measurements of solid-density plasmas generated by fs laser pulses
    F. Zamponi, A. Lübcke, T. Kämpfer, I. Uschmann, E. Förster, R. Sauerbrey, B. Hidding, M. Clever, G. Pretzler, E. Kroupp, E. Stambulchik, D. Fisher, Y. Maron, R. Sharon, M. Deutsch
    High Energy Density Phys. 3, 297 (2007)

  • Acoustic phonons in InSb probed by time-resolved X-ray diffraction
    A. Morak, T. Kämpfer, I. Uschmann, A. Lübcke, E. Förster, R. Sauerbrey
    phys. stat. sol. (b) 243, 2728 (2006)

  • Optical Switching of fs laser produced Ka-radiation using the Borrmann effect
    A. Lübcke, I. Uschmann, A. Morak, H. Schwörer, E. Förster, R. Sauerbrey
    Appl. Phys. B 80, 801 (2005)

  • Spatial characteristics of Ka x-ray emission from relativistic femtosecond laser plasmas
    C. Reich, I. Uschmann, F. Ewald, S. Düsterer, A. Lübcke, H. Schwoerer, R. Sauerbrey, E. Förster, P. Gibbon
    Phys. Rev. E 68, 056408 (2003)