Amid a fast game in a vast venue, sports photography seeks to freeze motion and isolate small portions of space for special consideration. In the scientific world of the ultrafast and ultrasmall, stroboscopic effects are achieved with greatly attenuated laser pulses. The advent of laser light served up in femtosecond (or 10^-15 second) bursts has helped to elucidate the molecular world by freezing their vibrational and rotational motions. Scientists would of course like to instigate and monitor even shorter times and distances.
A collaboration between scientists at the Technical University of Vienna and the Max Planck Institute for Quantum Optics (MPQ) has now done precisely this. They have produced a series of 2.5-fsec pulses, each consisting of only a few cycles of a carrier light signal modulated within an amplitude envelope. In the case of the Vienna-MPQ experiment, however, all the pulses are identical (a feat not achieved previously) and the phase of the carrier wave within the envelope is controlled with a time resolution of about 100 attoseconds.
When the intense (100 GW) few-cycle pulse strikes an atom, an electron can be stripped away quickly, and reabsorbed just as quickly. This violent excursion results in the emission of a sharp x-ray spike with a duration even shorter than the pulse that excited the reaction. In fact the x-ray pulses are about 500 attoseconds long. Moreover, because all the waveforms of the optical pulse are identical, and controlled, the subsequent electron motions and x-ray emissions are also highly controlled and reproducible. At a talk at this weeks meeting of the American Association for the Advancement of Science (AAAS) in Denver, Vienna physicist Ferenc Krausz said that this sub-femtosecond control of electron currents represented true attophysics, a new technique for directing and watching atomic processes at unprecedentedly short time intervals. (See Baltuska et al., Nature, 6 February 2003.)
Phillip F. Schewe | PHYSICS NEWS UPDATE
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Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
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Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
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An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
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