Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultra-short X-ray pulses explore the nano world

25.11.2014

Characterization of X-ray flashes open new perspectives in X-ray science

Ultra-short and extremely strong X-ray flashes, as produced by free-electron lasers, are opening the door to a hitherto unknown world. Scientists are using these flashes to take “snapshots” of the geometry of tiniest structures, for example the arrangement of atoms in molecules.


Undulator hall at the Linac Coherent Light Source of SLAC

Photo: SLAC National Accelerator Center

To improve not only spatial but also temporal resolution further requires knowledge about the precise duration and intensity of the X-ray flashes. An international team of scientists has now tackled this challenge.

X-ray flashes are a unique scientific tool. They are generated by accelerating electrons to very high energy levels in kilometer-long vacuum tubes, so-called linear accelerators, and then deflecting them with specially arranged magnets. In the process the particles emit X-ray radiation that is amplified until an ultra-short and intensive X-ray flash is released.

Researchers use these X-ray flashes to resolve structures as small as one ten billionth of a meter (0.1 nanometer) in size. That is roughly the diameter of a hydrogen atom. In this way, biomolecules, for example, can be imaged at extremely high resolution, providing new insight into the nano cosmos of nature.

Using two quickly sequenced flashes the researchers can even obtain information on structural changes during reactions. The first laser flash triggers a reaction while the second measures structural changes during the reaction. For this it is essential to know the precise duration and temporal intensity distribution of the X-ray flashes. However, hitherto it has not been possible to measure the ultra-short pulses directly.

Researchers at the Technische Universität München (TUM), the Hamburg Center for Free-Electron Laser Science (CFEL) and the Max Planck Institute of Quantum Optics (MPQ) in Garching, in collaboration with other colleagues, have now developed just such a methodology. The respective experiments were done at the SLAC National Accelerator Laboratory in California (USA) by a team headed by Professor Reinhard Kienberger, Dr. Wolfram Helml (TUM) and Dr. Andreas Maier (CFEL).

The scientists determined the duration of the X-ray flashes by modifying a process originally developed to measure ultra-short flashes of light. The physicists directed the X-ray flashes into a vacuum chamber filled with a few atoms of an inert gas. There they superimposed the flashes with 2.4 micrometer wavelength pulses of infrared light.

When the X-ray flashes hit a gas atom they knock electrons out of the innermost shell, setting them free. After being liberated the electrons are accelerated or decelerated by the electrical field of the infrared light pulse. The change in an electron’s velocity is a function of when the light intercepts the electron, and thus of the electrical field strength at the moment of ionization.

Since electrons are set free during the full duration of an X-ray flash, electrons emitted at different points in time “feel” different field strengths of the periodically oscillating infrared light. As a result they are accelerated at varying rates. The physicists can then calculate the duration of the original X-ray flash from the different arrival times of the electrons in a detector.

Using this approach, the researchers determined that the average pulse duration doesn’t exceed four and a half femtoseconds – a femtosecond is a millionth of a billionth of a second (10-15 seconds). In addition, the researchers obtained insight into the structure of the X-ray flashes.

A characteristic of the intense X-ray flashes generated in free-electron lasers is their randomly changing pulse form. A typical X-ray pulse comprises multiple contiguous shorter “X-ray spikes.” The number and intensity of these spikes varies from one shot to the next.

For the first time ever, the researchers managed to measure these ultra-short sub-peaks directly and confirm predictions that the individual flashes last only around 800 attoseconds – an attosecond is a billionth of a billionth of a second (10-18 seconds). The new methodology allows the detailed, direct temporal measurement of X-ray pulses and augments methodologies for determining pulse shape and length indirectly from the structure of the electron packets used to generate the flashes.

The enhanced X-ray pulse measurement technology may also find application at the new Center for Advanced Laser Applications (CALA) at the Garching campus. Researchers there are working on, among other things, generating even shorter X-ray pulses using high-energy lasers. Pulses with a duration of only a few attoseconds, would allow researchers to take “snapshots” of even faster processes in nature, like the movement of electrons around atomic nuclei.

However, X-ray flashes provide not only basic research with new perspectives. Medicine could also profit from the technology. “Ultra-short laser-like X-ray pluses serve not only the investigation of the fastest physical processes at the core of matter, but could, because of their extremely high intensity, also be used to destroy tumors following X-ray diagnosis,” explains Reinhard Kienberger, professor for laser and X-ray physics at TU München and leader of the research consortium.

The research was funded by the German Research Foundation (Excellence Cluster Munich – Center for Advanced Photonics, MAP), the Bavaria California Technology Center (BaCaTec), the International Max Planck Research School on Advanced Photon Science (IMPRS), a Marie Curie International Outgoing Fellowship, the US Department of Energy, the National Science Foundation (USA), the Science Foundation Ireland (SFI) and the European Research Council (ERC Starting Grant). CFEL is a collaboration facility of the Deutsches Elektronen Synchrotron (DESY), the University of Hamburg and the Max Planck Society. CALA is a joint research facility of Technische Universität München and Ludwig-Maximilians-Universität München.

Publication:

W. Helml, A. R. Maier, W. Schweinberger, I. Grguraš, P. Radcliffe, G. Doumy, C. Roedig, J. Gagnon, M. Messerschmidt, S. Schorb, C. Bostedt, F. Grüner, L. F. DiMauro, D. Cubaynes, J. D. Bozek, Th. Tschentscher, J. T. Costello, M. Meyer, R. Coffee, S. Düsterer, A. L. Cavalieri & R. Kienberger
Measuring the temporal structure of few-femtosecond FEL X-ray pulses directly in the time domain
Nature Photonics online, 24. November 2014, Doi: 10.1038/NPHOTON.2014.278

Contact:

Prof. Dr. Reinhard Kienberger
Technische Universität München
Chair for Laser and X-Ray Physics, E11
James Frank Str., 85748 Garching, Germany
Tel.: +49 89 289 12840 – E-mail: reinhard.kienberger@tum.de
Internet: www.e11.ph.tum.de

Dr. Andreas Battenberg | EurekAlert!
Further information:
http://www.tum.de/en/about-tum/news/press-releases/short/article/31913/

More articles from Physics and Astronomy:

nachricht Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>