Their achievement currently represents the shortest artificial light pulse that has been reported in a refereed journal. Shining this ultrashort light pulse on atoms and molecules can reveal new details of their inner workings—providing benefits to fundamental science as well as potential industrial applications such as better controlling chemical reactions. Working at Italy's National Laboratory for Ultrafast and Ultraintense Optical Science in Milan (as well as laboratories in Padua and Naples), the researchers believe that their current technique will allow them to create even shorter pulses well below 100 attoseconds. Results will be presented in Baltimore at CLEO/QELS, May 6 – May 11.
Whereas humans perceive the world in terms of seconds and minutes, the electrons in atoms and molecules often perform actions on attosecond time scales. How short is this? 130 attoseconds is to one second as a second is to approximately 243 million years—roughly the time that has passed since the first dinosaurs walked the Earth. Aiming a human-made attosecond-scale light pulse on atoms and molecules can trigger new effects in electrons—which are responsible for all chemical reactions—and provide new details on how they work.
In previous experiments, longer pulses, in the higher hundreds of attoseconds, have been created, and the general process is the same. An intense infrared laser strikes a jet of gas, usually argon or neon. The laser’s powerful electric fields rock the electrons back and forth, causing them to release a train of attosecond pulses consisting of high-energy photons in the extreme ultraviolet or soft x-ray part of the spectrum.
Creating a single isolated attosecond pulse, rather than a train of them, is more complex. To do this, the researchers employ their previously developed technique for delivering intense short (5 femtoseconds, or millionths of a billionth of a second) laser pulses to an argon gas target. They use additional optical techniques (including ones borrowed from the research that won the 2005 Nobel Prize in Physics) for creating and shaping a single attosecond pulse. These isolated attosecond pulses promise to probe electron phenomena such as "wavepackets"—specially tailored electron waves inside atoms and molecules that may help scientists use lasers to change the course of chemical reactions for scientific and practical uses, such as controlling the breaking of bonds in complex molecules for medical and pharmaceutical applications.
Four elements make 2-D optical platform
26.09.2017 | Rice University
The material that obscures supermassive black holes
26.09.2017 | Instituto de Astrofísica de Canarias (IAC)
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
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26.09.2017 | Physics and Astronomy
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