Caption: The x-ray laser investigates the change in the electron structure when CO molecules desorb from a metal surface of ruthenium. Roughly 30% of the molecules are pumped up with the aid of a femtosecond of optic laser from the surface-bonded (“chemisorbed”) state to a transient intermediate state (“precursor”) where they interact faintly with the surface. By examining the molecules with the x-ray laser with varying delay periods, it is possible to show that the time scale for achieving the precursor state is a few picoseconds and that they exist there for a few tens of picoseconds before either leaving the surface entirely or returning to the surface.
In the experiment, CO molecules were dosed onto a metal surface of ruthenium, which is used in automobile catalytic converters, for instance. CO binds strongly to the surface but can be made to let go by heating up the surface, which was done with a pulse from an optical laser. By starting the reaction for all the molecules at the same time, the team got a sufficient number of molecules to simultaneously enter a state where they have almost let go of the surface but still have a weak binding to it. From this short-lived state, the molecules can then continue out into a gas phase or renew their bond when the surface cools down again.“Scientists have long speculated whether such a state, a so-called ‘precursor,’ exists. The new experiment is the first to directly show its existence,” says Lars G. M. Pettersson at the Department of Physic, Stockholm University. These studies will not go on to more complex reactions of interest to the field of synthetic fuels, among other applications.
DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences