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.
UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire
NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences