Press releases


Jun 15 2020

Frankfurt researchers deliver experimental proof for a 90 year-old theory

Atomic physics: radiation pressure with recoil

FRANKFURT. Light exerts a certain amount of pressure onto a body: sun sails could thus power space probes in the future. However, when light particles (photons) hit an individual molecule and knock out an electron, the molecule flies toward the light source. Atomic physicists at Goethe University have now observed this for the first time, confirming a 90 year-old theory.

As early as the 16th century, the great scholar Johannes Kepler postulated that sunlight exerted a certain pressure, as the tail of the comets he observed consistently pointed away from the sun. In 2010 the Japanese space probe Ikaros used a sun sail for the first time in order to use the power of sunlight to gain a little speed.

Physically and intuitively, the pressure of light or radiation can be explained by the particle characteristic of light: light particles (photons) strike the atoms of a body and transfer a portion of their own momentum (mass times speed) onto that body, which thus becomes faster.

However, when in the 20th century physicists studied this momentum transfer in the laboratory during experiments on photons of certain wavelengths which knocked individual electrons out of atoms, they were met by a surprising phenomenon: the momentum of the ejected electron was greater than that of the photon that struck it. This is actually impossible – since Isaac Newton it has been known that within a system, for every force there must exist an equal but opposite force: the recoil, so to speak. For this reason, the Munich scientist Arnold Sommerfeld concluded in 1930 that the additional momentum of the ejected electron must come from the atom it left. This atom must fly in the opposite direction; in other words, toward the light source. However, this was impossible to measure with the instruments available at that time.

Ninety years later the physicists in the team of doctoral student Sven Grundmann and Professor Reinhard Dörner from the Institute for Nuclear Physics have succeeded for the first time in measuring this effect using the COLTRIMS reaction microscope developed at Goethe University Frankfurt. To do so, they used X-rays at the accelerators DESY in Hamburg and ESRF in French Grenoble, in order to knock electrons out of helium and nitrogen molecules. They selected conditions that would require only one photon per electron. In the COLTRIMS reaction microscope, they were able to determine the momentum of the ejected electrons and the charged helium and nitrogen atoms – which are called ions – with unprecedented precision.

Professor Reinhard Dörner explains: “We were not only able to measure the ion’s momentum, but also see where it came from – namely, from the recoil of the ejected electron. If photons in these collision experiments have low energy, the photon momentum can be neglected for theoretical modelling. With high photon energies, however, this leads to imprecision. In our experiments, we have now succeeded in determining the energy threshold for when the photon momentum may no longer be neglected. Our experimental breakthrough allows us to now pose many more questions, such as what changes when the energy is distributed between two or more photons.”

Publication: Sven Grundmann, Max Kircher, Isabel Vela-Perez, Giammarco Nalin, Daniel Trabert, Nils Anders, Niklas Melzer, Jonas Rist, Andreas Pier, Nico Strenger, Juliane Siebert, Philipp V. Demekhin, Lothar Ph. H. Schmidt, Florian Trinter, Markus S. Schöffler, Till Jahnke, and Reinhard Dörner: Observation of Photoion Backward Emission in Photoionization of He and N2. Phys. Rev. Lett. 124, 233201

Further information:

Prof. Dr. Reinhard Dörner
Institute for Nuclear Physics
Tel. +49 69 798-47003


Jun 12 2020

Goethe University physicists develop free covid-19 analysis website to compare the number of cases and deaths by country

Comparing covid-19 data worldwide with a click of the mouse  

FRANKFURT. There is no lack of data on global corona developments. But if you want to actively compare countries yourself and relate case and death figures across countries, you can now get a quick overview with just a few clicks – and gain surprising insights in the process.

The new web service “Goethe Interactive Covid-19 Analyzer“ which Fabian Schubert in the working group for the theory of complex systems at the Institute for Theoretical Physics developed alongside his dissertation is simple to use: go to the “Goethe Interactive Covid-19 Analyzer” website, click on the countries and number of cases in questions, and drag the curves over each other. Congruent? The answer is immediately visible. In the same way – depending on the individual question - the daily number of cases or deaths, or the total number of infected or deceased individuals can be compared. The underlying data for countries from “A” as in Afghanistan through “Z” as in Zimbabwe is provided by the known covid-19 databases of the European Centre for Disease Control” and the “Johns HopkinsCenter For Systems Science and Engineering.”

“Our interactive tool allows researchers, journalists and other interested parties to quickly gain an overview of outbreak developments,” explains Professor Claudius Gros, who studies the modelling of covid-19 outbreaks himself at the Institute for Theoretical Physics, and who as Schubert’s doctoral advisor encouraged him to develop the service tool. Those who use the tool may also discover relationships that provide inspiration for additional research on epidemic processes.

Gros, for example, was surprised that the scaled trajectory curves of the case numbers from Germany and Spain “are almost identical, although the two countries pursued significantly different lockdown measures.” There are also interesting clues regarding the unexplained issue of the number of unrecorded cases of corona infections. For Italy, the scaled curve of covid-19 infections corresponds to the curve of corona deaths if the daily case numbers are applied to the total numbers of the sick or the deceased. “This indicates that the unrecorded case numbers may not have changed significantly over the course of the outbreak – even though testing increased.”

The “Goethe Interactive Covid-19 Analyzer” from the Institute for Theoretical Physics offers numerous options for combining data per mouse click. “The page has only been live for a couple of days,”  says Gros. It therefore remains to be seen how many researchers and other interested parties will use the new analytical tool. The first scientists have already indicated interest, however. And the theoretical physicist is certain: “The website is certainly useful for the final papers and doctoral dissertations on covid-19 that will soon be written. And also for secondary school students who want to present a paper on corona.”

The new analytic tool is hosted on the webserver  of the Institute for Theoretical Physics, which is also providing the necessary technical support.

Website: Goethe Interactive Covid-19 Analyzer:

Publication: Claudius Gros, Roser Valenti, Kilian Valenti, Daniel Gros, Strategies for controlling the medical and socio-economic costs of the Corona pandemic (2020);

Further information: Prof. Dr. Claudius Gros, Institut für Theoretische Physik, Campus Riedberg, E-Mail


Jun 10 2020

Frankfurt researchers use ecological niche modelling to project the distribution of Chagas disease vectors 

Kissing bugs also find suitable climatic conditions in Europe

FRANKFURT. An infection with Chagas disease is only possible in Latin America since the insect species that spread the disease only occur there. Scientists at Goethe University and the Senckenberg Society for Natural Research have now used ecological niche models to calculate the extent to which habitats outside of the Americas may also be suitable for the bugs. The result: climatically suitable conditions can be found in southern Europe for two kissing bug species; along the coasts of Africa and Southeast Asia the conditions are suitable for yet another species. The Frankfurt scientists therefore call for careful monitoring of the current distribution of triatomine bugs. (eLife DOI: 10.7554/eLife.52072)

The acute phase of the tropical Chagas disease (American Trypanosomiasis) is usually symptom-free: only in every third case does the infecting parasite (Trypanosoma cruzi) cause any symptoms at all, and these are often unspecific, such as fever, hives and swollen lymph glands. But the parasites remain in the body,  and many years later chronic Chagas disease can become life-threatening with pathological enlargement of the heart and progressive paralysis of the gastrointestinal tract. There is no vaccine for Chagas disease. The WHO estimates that 6 to 7 million people are infected worldwide, with the majority living in Latin America (about 4.6 million), followed by the USA with more than 300,000 and Europe with approximately 80,000 infected people.

Chagas parasites are transmitted by predatory blood-sucking bugs that ingest  the pathogen along with the blood. After a development period in the intestinal tract of the bugs, the parasites are shed in the bug's faeces. The highly infectious faeces are unintentionally rubbed into the wound by the extreme itching caused by the bug bite. Oral transmission by eating food contaminated with  triatomine bug faeces is also possible.

Researchers led by the Frankfurt parasitologists and infection biologists Fanny Eberhard and Professor Sven Klimpel have used niche models to investigate which climatic conditions in the world are suitable for Latin American kissing bugs. In particular, temperature and precipitation patterns were incorporated into the calculations on the climatic suitability of a region. The researchers were able to show that currently in addition to Latin America, Central Africa and Southeast Asia also have suitable habitats for triatomines. Two of the triatomine species, Triatoma sordida and Triatoma infestans, are now finding suitable habitats in temperate regions of southern Europe such as Portugal, Spain, France and Italy. Both triatomine species frequently transmit the dangerous parasites in Latin America and can be found inside or near houses and stables, where they get their nightly blood meals preferably from dogs, chickens and  humans.

Another triatomine species, Triatoma rubrofasciata, has already been detected outside Latin America. The model calculations by the Frankfurt scientists identify suitable habitats along large areas of the African and Southeast Asian coasts.

Professor Sven Kimpel explains: “There are people living in Europe who were infected with Chagas in Latin America and are unknowingly carriers of Trypanosoma cruzi. However, the parasite can currently only be transmitted to other people through untested blood preservations or by a mother to her unborn child. Otherwise, Trypanosoma cruzi requires triatomine bugs as intermediate hosts. And these bugs are increasingly finding suitable climatic conditions outside Latin America. Based on our data, monitoring programmes on the distribution and spreading of triatomine bugs  would therefore be feasible. Mandatory reporting of Chagas disease cases could also be helpful."

Publication: Fanny E. Eberhard, Sarah Cunze, Judith Kochmann, Sven Klimpel. Modelling the climatic suitability of Chagas disease vectors on a global scale. eLife 2020;9:e52072 doi: 10.7554/eLife.52072,

An image may be downloaded here:

Caption: The triatomine or “kissing" bug Triatoma infestans. Credit: Dorian D. Dörge for Goethe University Frankfurt

Further information:
Prof. Dr. Sven Klimpel
Institute for Ecology, Evolution and Diversity, Goethe University
& Senckenberg Biodiversity and Climate Research Centre
Tel. +49 69 798 42237


Jun 9 2020

66 million euros to generate open-access chemical tools 

New consortium EUbOPEN will provide tools to unlock disease biology

Frankfurt and Ingelheim. Almost twenty years after deciphering the human genome, our understanding of human disease is still far from complete. One of the most powerful and versatile tools to better understand biology and disease-relevant processes is the use of well-characterized small chemical modulators of protein function. The new EUbOPEN consortium aims to develop high quality chemical tool compounds for 1,000 proteins (one third of the druggable proteins in the human body). It will enable unencumbered access to these research tools, thereby empowering academia and industry alike to explore disease biology and unlock the discovery of new drug targets and treatments.

The EUbOPEN consortium comprises 22 different partner organizations, including universities, research institutes, European Federation of Pharmaceutical Industries and Associations (EFPIA) members, and one small and medium-sized enterprise (SME). Goethe University Frankfurt and Boehringer Ingelheim are jointly leading the EUbOPEN consortium. Other partner organizations are Bayer AG, Diamond Light Source, EMBL-EBI, ETH Zürich, Fraunhofer IME, Georg-Speyer-Haus, Karolinska Institutet, Leiden University Medical Center, McGill University, Ontario Institute for Cancer Research, Pfizer, Royal Institute of Technology, Servier, the Structural Genomics Consortium, Takeda, University of Dundee, University of North Carolina, University of Oxford, and University of Toronto.

To interfere with the function of a protein in any given cell type, scientists need small chemical tools that affect the studied protein as specifically as possible, thereby avoiding unintended effects on other proteins. Therefore, there is an urgent need for selective and well-characterized chemical modulators for basic and applied research. Ideally, such tools would be available for every human protein. Moreover, these chemical modulators should be available to all researchers without restrictions on use, thus providing scientists with tools to better understand understudied proteins, thereby discovering possible links to disease.

The generation and dissemination of such high-quality and well-characterized research tools for a substantial fraction of the druggable human genome are the major goals of the newly formed public-private partnership “Enabling and Unlocking biology in the OPEN" (EUbOPEN). This large consortium was launched on 1 May 2020, with a total budget of 65.8 million euros covered by a grant from the Innovative Medicines Initiative (IMI) and cash/in-kind contributions from EFPIA companies and IMI Associated Partners and contributions from partners outside of Europe.

'EUbOPEN will provide the wider academic community with unencumbered access to the highest quality pharmacological tool compounds for a large number of novel targets, and seed a massive community target prioritization and deconvolution effort. The expected impact should be transformative', says Project Leader Adrian J. Carter, Boehringer Ingelheim.

'By the end of the project, we will have created the largest and most deeply characterised collection of chemical modulators of protein function that is openly available. The chemical tool sets and associated data will be a tremendous resource for academic science leading to the discovery of new biology and of novel disease modulating targets for the development of new medicines', adds Coordinator Stefan Knapp, Goethe University Frankfurt.

EUbOPEN will develop these compounds using new technologies and test them in well-characterized, disease-relevant human tissue assays in the areas of immunology, oncology and neuroscience. The project outputs, including chemogenomic library sets, chemical probes, assay protocols and associated research data will be made openly available to the research community without restriction.

The EUbOPEN project will form the foundation for future global efforts to generate chemical modulators for the entire druggable proteome and the developed new technologies will significantly shorten the lead optimization processes. The sustainability of the resources the project will be ensured through many partnerships for example with chemical vendors and biotech companies as well as online database providers. Internet:

Innovative Medicines Initiative (IMI)

The IMI is Europe's largest public-private initiative aiming to speed up the development of better and safer medicines for patients. IMI supports collaborative research projects and builds networks of industrial and academic experts in order to boost pharmaceutical innovation in Europe. IMI is a joint undertaking between the European Union and the European Federation of Pharmaceutical Industries and Associations (EFPIA).

For further details please visit:

Further information:

Goethe-University Frankfurt:

Prof. Dr. Stefan Knapp
EUbOPEN Project Coordinator
Goethe University Frankfurt

Dr. Markus Bernards
Science Communications
P  +49 (69) 798 12498

Boehringer Ingelheim:

Dr. Adrian Carter
EUbOPEN Project Leader
Boehringer Ingelheim

Dr. Reinhard Malin
Head of Communications Innovation Unit
P: + 9 (6132) 77 90815


Jun 9 2020

New experimental technique with Goethe University’s reaction microscope allows “X-ray” of individual molecules

Snapshot of exploding oxygen

FRANKFURT. For more than 100 years, we have been using X-rays to look inside matter, and progressing to ever smaller structures – from crystals to nanoparticles. Now, within the framework of a larger international collaboration on the X-ray laser European XFEL in Schenefeld near Hamburg, physicists at Goethe University have achieved a qualitative leap forward: using a new experimental technique, they have been able to “X-ray" molecules such as oxygen and view their motion in the microcosm for the first time.

“The smaller the particle, the bigger the hammer." This rule from particle physics, which looks inside the interior of atomic nuclei using gigantic accelerators, also applies to this research. In order to “X-ray" a two-atom molecule such as oxygen, an extremely powerful and ultra-short X-ray pulse is required. This was provided by the European XFEL which started operations in 2017 and is one of the the strongest X-ray source in the world

In order to expose individual molecules, a new X-ray technique is also needed: with the aid of the extremely powerful laser pulse the molecule is quickly robbed of two firmly bound electrons. This leads to the creation of two positively charged ions that fly apart from each other abruptly due to the electrical repulsion. Simultaneously, the fact that electrons also behave like waves is used to advantage. “You can think of it like a sonar," explains project manager Professor Till Jahnke from the Institute for Nuclear Physics. “The electron wave is scattered by the molecular structure during the explosion, and we recorded the resulting diffraction pattern. We were therefore able to essentially X-ray the molecule from within, and observe it in several steps during its break-up."

For this technique, known as “electron diffraction imaging", physicists at the Institute for Nuclear Physics spent several years further developing the COLTRIMS technique, which was conceived there (and is often referred to as a “reaction microscope"). Under the supervision of Dr Markus Schöffler, a corresponding apparatus was modified for the requirements of the European XFEL in advance, and designed and realised in the course of a doctoral thesis by Gregor Kastirke. No simple task, as Till Jahnke observes: “If I had to design a spaceship in order to safely fly to the moon and back, I would definitely want Gregor in my team. I am very impressed by what he accomplished here."

The result, which was published in the current issue of the renowned Physical Review X, provides the first evidence that this experimental method works. In the future, photochemical reactions of individual molecules can be studied using these images with their high temporal resolution. For example, it should be possible to observe the reaction of a medium-sized molecule to UV rays in real time. In addition, these are the first measurement results to be published since the start of operations of the Small Quantum Systems (SQS) experiment station at the European XFEL at the end of 2018.

Photoelectron diffraction imaging of a molecular breakup using an X-ray free-electron laser. Gregor Kastirke et al. Phys. Rev. X 10, 021052

Images may be downloaded at this link:

Caption: During the explosion of an oxygen molecule: the X-ray laser XFEL knocks electrons out of the two atoms of the oxygen molecule and initiates its breakup. During the fragmentation, the X-ray laser releases another electron out of an inner shell from one of the two oxygen atoms that are now charged (ions). The electron has particle and wave characteristics, and the waves are scattered by the other oxygen ion. The diffraction pattern are used to image the breakup of the oxygen molecules and to take snapshots of the fragmentation process (electron diffraction imaging). Credit: Till Jahnke, Goethe University Frankfurt

Further information:
Professor Till Jahnke
Institute for Nuclear Physics
Goethe University Frankfurt
Tel.: +49 69 798-47025

For European XFEL und SQS:
Dr. Michael Meyer
Holzkoppel 4
22689 Schenefeld
Tel.: 040 8998 5614