A team of physicists and chemists from the University of Rostock, the Laboratory of Attosecond Physics at the Ludwig-Maximilians-Universität, the Max Planck Institute of Quantum Optics, and Freie Universität Berlin has studied the interaction of light with tiny glass particles.
The relationship between strong laser pulses and glass nanoparticles is a special one – one that could influence medical methods, as scientists from Rostock, Munich, and Berlin have discovered. The interplay between light and matter was studied by a team of physicists and chemists from the Laboratory of Attosecond Physics (LAP) at the Max Planck Institute of Quantum Optics (MPQ) and the Ludwig-Maximilians-Universität Munich (LMU), from the Institute of Physics of the University of Rostock, and from Freie Universität Berlin.
The researchers studied the interaction between strong laser pulses and glass nanoparticles, which consist of multiple millions of atoms. Depending on how many atoms were contained in the nanoparticles, these objects reacted differently over attosecond timescales (an attosecond is a billionth of a billionth of a second).
Depending on their size, so called near-fields (electromagnetic fields close to the particle surface) were induced by the laser pulses, resulting in a controlled directional emission of electrons. These findings could eventually extend cancer therapy and imaging methods in medicine. The study was published in the latest issue of the journal Nature Communications.
Strong laser pulses have an extremely pronounced effect on nanoparticles. As soon as the atoms “feel” the electromagnetic wave of the light, their electrons start to oscillate. This produces near-fields at the surface of the particles. These near-fields have dimensions in the nanometer range, and oscillate in a characteristic fashion depending on the wavelength of the incident light.
Led by Prof. Matthias Kling, the LAP-physicists studied silica nanospheres with diameters of 50 to 550 nanometers, which were chemically synthesized in the research group around Eckart Rühl at Freie Universität Berlin.
The scientists let strong, approximately four-femtosecond-long laser pulses hit the group of atoms (a femtosecond is a millionth of a billionth of a second). As soon as the electromagnetic waves of the light field hit the nanospheres, near-fields formed at the surface and began to pulsate. The larger the light-irradiated spheres were compared to the laser wavelength (720 nanometers), the stronger the effect of the near-fields as an electron catapult.
The researchers observed this effect by using particle detectors to monitor the flight paths of electrons emitted from the near-fields of the nanospheres within the passage of the laser pulse. “The energy and direction of emitted electrons is strongly linked to the spatial and temporal structure of the near-fields. The emission of electrons is like a ping-pong game on the surface of the nanospheres that can be controlled with a precision of attoseconds,” explains Prof. Thomas Fennel from the University of Rostock.
He conducted simulations with his team, shedding light on the microscopic processes and their evolution in time. “First, the electrons leave the spheres, but they are then pulled back to their surface. After bouncing off the surface, they obtain a strong, final momentum kick from the near-field, which frees them from the nanoparticles,” Prof. Matthias Kling added.
Since the directional emission of particles can be controlled with this technique using laser light, the researchers argue that a long-term perspective could be medical applications. “With directional electron motion, strongly directed X-rays for imaging applications could be produced,” describes Prof. Eckart Rühl.
With sufficiently intense laser pulses, it may also be possible to release ions, which are charged atoms, from the nanocomposite, resulting in strongly directed ion radiation for cancer therapy. Furthermore, the technique might open up new perspectives for material processing beyond the diffraction limit – for instance in order to remove nanometer-sized areas from a surface.
The scientists also believe that the combination of strong light pulses and nanoparticles can become an important building block of future electronics. With so-called light wave electronics, one would be able to compute data at light wave frequency (about 1015 cycles per second): 100,000 times faster than currently possible. (Thorsten Naeser)
Field propagation-induced directionality of carrier-envelope phase-controlled photoemission from nanospheres.
F. Süßmann, L. Seiffert, S. Zherebtsov, V. Mondes, J. Stierle, M. Arbeiter, J. Plenge, P. Rupp, C. Peltz, A. Kessel, S.A. Trushin, B. Ahn, D. Kim, C. Graf., E. Rühl, M.F. Kling, T. Fennel.
Nature Communications, 12. August 2015, DOI: 10.1038/ncomms8944
Contacts for further information:
Prof. Dr. Matthias Kling
Ultrafast Nanophotonics Group, Laboratory for Attosecond Physics
Department of Physics, Am Coulombwall 1
85748 Garching, Germany
Prof. Dr. Eckart Rühl
Institut für Chemie und Biochemie - Physikalische und Theoretische Chemie
Freie Universität Berlin
14195 Berlin, Germany
Prof. Dr. Thomas Fennel
Theoretical Cluster Physics and Nanophotonics Group
Institute of Physics, University of Rostock
18051 Rostock, Germany
Ingrid Rieck | Universität Rostock
Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University
Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology
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,...
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...
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...
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...
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...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences