Blog Archives

The division of Prof. Thomas Pfeifer, focusing on the fundamental physics of quantum dynamics and control at the Max Planck Institut für Kernphysik at Heidelberg, (Germany), offers a stimulating and international research environment and invites applications for

Post-Doctoral Research Associates
with or without group-leader function
depending on scientific qualification and standing

Research Area:
– Time-resolved control and precision spectroscopy/metrology, especially regarding x-ray (>10 keV) nuclear transitions on the nano-, pico-, and femto-second scale
– Mössbauer spectroscopy with natural isotopes and pulsed synchrotron/free-electron Laser (FEL) light sources

Your Profile:
– A doctoral degree or PhD in physics
– Prior experience with some experimental techniques mentioned above certified by publications with contributions as a main author
– Highly beneficial: Experience with femtosecond spectroscopy and/or control, in the best case applied to lattice vibrations / phonons

The salary will be paid according to the collective agreement for civil service employees (TVöD) and includes additional retirement benefits (VBL). The details will depend on the qualification of the applicant. The contract period is for 2 years with the possibility of extension.

Further information about our research division can be found

Please apply ONLINE no later than 15 December 2015. Required documents: cover letter (reference # 18 -2015), CV, research statement, publication list, copy of doctoral/PhD diploma and contact details of at least three referees.

Download full information about this position in pdf format here: 18-2015_Postdocs_Pfeifer_engl

There is a 2 year postdoctoral position in quantum dynamics method development available at the Cecam headquarters at EPF-Lausanne. This position is part of the E-CAM project supporting European e-infrastructure. The position is to work with Sara Bonella (Cecam), Ivano Tavernelli (IBM) and Graham Worth (Birmingham) on (1) developing and comparing methods for treating open systems (2) developing algorithms for quantum dynamics on a quantum computer. For further details see:

Closing date is Dec. 20th 2015.

Graham Worth

The structure function relationship is an important fundamental concept in the molecular sciences. In this project attosecond electron dynamics of complex molecules will be investigated for different structural isomers of complex molecules. In close collaboration with theory, this will provide a direct measurement of the structure-function relationship with respect to the electronic, i.e., chemical, properties of the molecules.

The early-stage researcher (ESR) will be an integral part of the MEDEA network and will be the driving force of the experiments to investigate conformer-specific attosecond dynamics in complex molecules. The work will be performed primarily at DESY/CFEL and in close collaboration with the network nodes at Politecnico di Milano and Aarhus University as well as the partner node in Heidelberg, which will provide theoretical support. Moreover, collaboration with as well as a secondment at the industrial partner Photek is foreseen.

The project does include significant outreach activities. This includes the teaching of high-school students by the ESR, using the Photonics Explorer toolkit provided by the network/EYEST.

A successful candidate will have a background in experimental physics or a related field. The EU ITN requires mobility and the candidate must have spend less than 12 month of the last 3 years in Germany. Salary is according to EU standards for a full position (i.e., very good).

Please see our website for further details, including

STSM by Christina Kjaer Soerensen, Aarhus University (DK) with Yoni Toker, Bar Ilan University (IL)
On September 5, 2015 (6 days)

Mass spectrometric analysis of chlorophyll cluster ions produced by electrospray ionization

The purpose of the STSM was to study which chlorophyll dimers or larger clusters that can be formed with electrospray ionisation using the high resolution Agilent q-TOF Mass Spectrometer located at Bar Ilan University in Israel.Chlorophyll_a_R1_ach
Chlorophyll (Chl) a and b are the light-absorbers of plants and are composed of a porphyrin macrocycle with a divalent magnesium ion in the center. The pi − pi* transitions in the porphyrin are responsible for the strong UV/Vis absorption by these molecules. It is non-trivial to predict the absorption spectra of Chl a and b, and what effect the in vivo protein environment has. Accordingly, it is interesting to study absorption by isolated chlorophylls in vacuo, which was previously obtained indirectly from action spectroscopy.
Exciton coupling between two or more chlorophylls is expected to have a significant effect on the absorption spectrum, and by comparing the absorption by the dimers to that of the monomers, the strength of these couplings can be identified through band splitting / broadening or shifts. In order to obtain the absorption spectra of the dimers, it is necessary to determine which dimer or cluster complexes can be made with electrospray ionisation.
During the STSM, different solvents, temperatures and other settings of the system were tested in the attempt of producing dimers or larger cluster complexes with a quaternary ammonium cation (tetramethylammonium and acetylcholine), as these are used for charge tagging the neutral Chl molecule in order to perform gas-phase action spectroscopy.
One out of many obtained mass spectra is shown in Figure 1. This is the mass spectrum of Chl a and the charge tag acetylcholine (ACh) in the mass to charge ratio range 1740-1815. The highest yield in this range is from the protonated dimer consisting of two Chl a with one magnesium ion replaced by two hydrogen atoms (m/z 1764.1). The shape of the peak distribution arise from isotopic species. Two other interesting dimers are produced with weak intensities: the protonated Chl a dimer (m/z 1786.1) and protonated dimer of two Chls with both magnesium ions replaced (m/z 1742.1). However, the dimer-tag complex with both magnesium ions was not present in any of the obtained spectra.
The process of replacing the magnesium center in Chl also occurs in nature and is the reason why leaves lose the green color in the fall. From the obtained spectra it can be concluded that complexes of Chl a without the magnesium ion are easily produced with high intensity. This gives the opportunity of studying the absorption by the “fall-Chl” in Aarhus.
Additionally, the spectra show that the protonated dimers are possible to produce and this gives hope for producing dimers tagged with the cations. These complexes are more fragile, and more work is required in optimising the conditions in order to produce these. This work continues after the STSM and hopefully brings the desired results and more knowledge and experience with producing such fragile biomolecules in gas-phase.
If the desired mass spectra are achieved, they will be applicable for a publication on the subject of absorption by Chl-dimer complexes. The already obtained spectra will be relevant in a future experimental study of the absorption by fall-Chls which hopefully also will deliver results to a
Furthermore, the collaboration between Bar Ilan University (Israel) and Aarhus University (Denmark) has been strengthened through this STSM.

CHRISK_imgFigure 1: Mass spectrum revealing the presence of more dimer-complexes. The highest signal is seen from a protonated Chl a dimer with one magnesium center replaced by two hydrogen atoms (m/z 1764). The signal at m/z 1786 is from a protonated Chl a dimer and at m/z 1742 the dimer with both magnesium replaced is observed.


STSM by Sylwia Stefanowska, Gdansk University of Technology (PL) with Alicja Domaracka, Center of Research on Ions Materials And Photonics (FR)
On August 1, 2015 (20 days)


Ion induced reactivity in molecular clusters

The aim of this Short Term Scientific Mission was to study collisions of 1-5keV Ar+ ions with PAH neutral clusters. The research was extended to acridine. This experiment has been performed to compare with anthracene (C14H10) and phenazine (C12H8N2) results and to understand how the presence of the nitrogen in a benzene ring can modify the molecular fragmentation and the reactivity of these kinds of molecules.
In the COLIMACON experiment pulsed beam of positive atomic ions collide with neutral particles in the interaction region of a linear time-of-flight mass spectrometer. Cationic products from individual collision events were detected in coincidence by microchannel plate detector. The Ar+ ions were produced by an ion gun, accelerated to 1.2 keV and pulsed into 1.5 μs bunches. The effusive jet of neutral particles of Acridine (C13H9N, 179 amu) was prepared using an isolated oven.
Measurements were carried out as a function of extraction delay, the extraction of cationic products is made a few μs after the interaction. Figure 1 presents the mass spectra for different delays of extraction, from 17.1 μs to 22.1 μs. It clearly appears that, with the increase of delay, the probability to lose one hydrogen atom from acridine molecule also increases. The analysis of the obtained data is still in progress.


STSM by Sandor Borbely, Babes-Bolyai University (RO) with Joachim Burgdörfer, Vienna University of Technology (AT)logo_ubb_albastru TU_logo
On August 9, 2015 (14 days)

Ionization and excitation of He by antiproton impact

During the interaction of high energy charged particles and atomic, molecular or solid targets the projectile loses parts of its energy. This energy is deposited in the target system via non-elastic processes like single or multiple ionization, excitations, etc. The relative importance of these energy deposition channels as a function of the projectile’s impact energy is a fundamental question is collision physics. This is also a key question during the assessment of the damage created by such high energy projectiles in biological tissues, since in biological systems after a charged projectile impact the most damage is caused by the residual charged targets created during the primary collision event. The chosen antiproton impact ionization and excitation of He is an ideal benchmark system for the investigation of the above mentioned energy loss processes.

For the antiproton-helium collision we have solved the electronic time-dependent Schrödinger equation numerically in the framework of the semiclassical impact parameter approach. From the obtained fully-correlated two-electron wave functions we have extracted the ionization and excitation probabilities, which were used to calculate the stopping power for each energy dissipation channel (single ionization, double ionization and single excitations). From these stopping powers the stopping cross sections were calculated by performing the impact parameter integrations. The obtained partial stopping cross sections are shown on the attached figure as a function of antiproton impact energy. On the figure one can observe that the dominant energy dissipation channel is single ionization followed by single excitations and double ionization. Since the present results are based on fully-correlated two-electron ab initio calculations, they can provide a reference for approximate calculations. After further analysis and comparison with the results of existing calculations and measurements the present results will be prepared for dissemination in the form of an article.


New Marie Skłodowska-Curie European Training Network: “ASPIRE”, Advance Announcement

The “ASPIRE” ITN-ETN will commence in March 2016 and will be recruiting twelve Early Stage Researchers (ESRs). Marie Skłodowska-Curie European Training Networks provide a unique experience for young researchers who benefit from secondments and travel opportunities as well as network based training and research.   Successful candidates will receive an attractive salary package, including generous mobility and family allowances, in accordance with the MSCA regulations for early stage researchers.

ASPIRE” stands for “Angular Studies of Photoelectron in Innovative Research Environments”.  The ASPIRE network will focus on the measurement of Molecular Frame Photoelectron Angular Distributions (MF-PADs), which can be interpreted as electron diffraction patterns achieved by “illuminating the molecule from within”, and enable the electronic structure and dynamics of molecules to be interrogated. Progress in this area is highly technologically driven, requiring ever more sophisticated light sources and faster detectors. The input of private sector beneficiaries and partner organizations is therefore critical to the scientific objectives, as well as to the enhanced training environment provided by the network.

The following groups and projects form the core of the ASPIRE network, alongside partner organizations in the academic and private sectors.  For more information on ASPIRE contact the Coordinator* or one of the group leaders listed below.

University of Nottingham


Goethe University Frankfurt

  • “Three-dimensional molecular frame photoelectron angular distributions from chiral molecules using circularly polarized light”, Reinhard Doerner,


  • “Development of a 3D detector for imaging experiments in a full spectrometer system”, Orla Kelly,

Universite Paris-Sud

  • “Probing ultrafast electronic and nuclear dynamics in molecules by spectrally & time resolved molecular frame photoelectron angular distributions”, Danielle Dowek,

Synchrotron SOLEIL

Aarhus University

  • “Molecular structure determination using molecular frame photoelectron angular distributions from strong field ionization”, Henrik Stapelfeldt,
  • “PADs from aligned molecules embedded in helium nanodroplets”, Henrik Stapelfeldt,

CNR-IFN and Politecnico di Milano

  • “Ultrafast Dynamic Imaging of Complex Molecules by Laser Induced Electron Diffraction”, Caterina Vozzi,

Max Born Institute, Berlin

A post doc position is available in the Lab. of Ultrafast Spectroscopy at the Ecole Polytechnique Fédérale de Lausanne, Switzerland.

The candidate is expected to conduct experiments at the Swiss Light Source synchrotron (SLS at the Paul-Scherrer-Institut, PSI, Villigen, Switzerland) and to prepare for the upcoming experiments at the SwissFEL free electron laser when it comes into operation in 2017. The experiments concern the study of the ultrafast structural dynamics of chemical (molecular and nano) and biological systems in solution. The lab. of Ultrafast Spectroscopy has complete equipment (laser system, detection and data acquisition systems, sample handling systems, etc.) at the SLS to conduct its research there. The candidate will be based at PSI-Villigen and will closely coordinate her/his activities with our partners of the SLS and SwissFEL. She/he will benefit from backing from the Lausanne lab for laser-only characterization experiments and technical support.

The position is for one year, renewable up to 4. It offers great perspectives for future career and growth given the current developments at Free Electron Laser facilities world-wide.

Applications and requests for more information to:

Professor Majed CHERGUI

Lab. of Ultrafast Spectroscopy (LSU) and Lausanne Centre for Ultrafast Science (LACUS)
Ecole Polytechnique Fédérale de Lausanne

The Doctoral Programme of Physics and Chemistry at the University of Turku has announced new funded PhD student positions.

The positions are for 4 years and the salaries are quite good in international comparison.

Good students who have recently graduated with a Master’s or equivalent degree and could be interested in pursuing doctoral studies abroad at the University of Turku are encouraged to contact Prof. Edwin Kukk at

The possible research fields are:
– Interaction of radiation with molecules and clusters, including
electron, ion and coincidence spectroscopy at home lab, synchrotron facilities and FELs
instrumental development
theoretical approaches and computational modeling
– Electron spectroscopic studies of surfaces and interfaces at home lab using various characterization techniques (ESCA, Auger, AFM, SEM) and at synchrotron facilities

Edwin Kukk, Prof.
Dept of Physics and Astronomy
University of Turku
Vesilinnantie 5
FI-20014 Turku, Finland
Tel: +35823336089

STSM by Inés Corral, Universidad Autonoma de Madrid (ES)  with Maurizio Persico, Universita di Pisa (IT)
On June 3rd, 2015 (63 days)

Competing ultrafast internal conversion and intersystem crossing in DNA and RNA modified nucleobases

The particular topology of the excited state potential energy surfaces (PES) of natural DNA monomers is the cornerstone of the photostability of our genetic material. [1] In fact, for these species the steeply descending nature of the spectroscopic state PES at the region connecting the Franck Condon geometry with the internal conversion funnel to the ground state prevents the retention of the wavepacket at interstate crossings, minimizing at the same time the transfer of population to lower lying excited states and other competing radiative emission processes, and therefore facilitates the relaxation of the population to the ground sate, Figure 1a. [2] This topology can be modified by altering the substitution pattern of the heterocyclic purine and pyrimidine skeleton, changing, thus, the intrinsic photophysical properties of natural nucleobases, Figure 1b.

This context frames the present STSM, along which we have explored the excited state deactivation dynamics of two modified nucleobases where one (4-thiothymine) or the two exocyclic oxygens (2,4-dithiothymine) of the natural nucleobase thymine have been substituted with sulfur atoms. To this purpose we have used the semiclassical surface-hopping algorithm developed in the group of Profs. Persico and Granucci, incorporating both non adiabatic and spin orbit couplings in the adiabatic representation. [3] These simulations were based on semiempirical PESs and couplings calculated from a reparameterized Hamiltonian with CASPT2 calculations. On the basis of these simulations we propose the following kinetic model for the deactivation of both systems: S2->S1->T2/T1. However, we also conclude, in agreement with previous experimental findings, [4] that the degree of substitution has a significant impact in the total triplet rise time, due to the very different excited state PESs topology predicted for both systems.

We expect to publish these results, together with the outcome of femtosecond broadband transient absorption experiments performed in the group of Prof. Crespo-Hernández from the Case Western Reserve University in Cleveland (Ohio), in a near future.

Fig-largeFigure 1. Schematic representation of potential energy surfaces characteristic of photostable (a) and photoreactive (b) chromophores.

[1] Photoinduced processses in nucleic acids Vols I, II, M. Barbatti, A.C. Borin, S. Ullrich (Eds.), Springer 2015.
[2] L. Serrano-Andrés, M. Merchán. J. Photochem. Photobiol. C 2009, 10, 21-32.
[3] G. Granucci, M. Persico, G. Spighi, J. Chem. Phys., 2012, 
137, 22A501.
[4] M. Pollum, S. Jockusch, C.E Crespo-Hernández, J. Am. Chem. Soc. 2014, 136, 17930.