Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Capturing electrons in action

20.07.2009
A technique for characterizing ultrafast light pulses will lead to better optical probes for studying electron dynamics

Scientists at RIKEN have developed a way to measure the wavelike properties of ultrafast (attosecond) light pulses—an important step toward being able to probe the dynamics of electrons, atoms and molecules.

Quantum mechanics theory can completely describe the structure of atoms and molecules. But directly observing electronic motion in an atom requires a technique that can take snapshots of the electron on time scales of less than a femtosecond (10-15 s). To this end, scientists are working to generate ultraviolet light pulses that are only 10–100 attoseconds (10-18 s) long.

Electrons, like light, have wavelike properties. Thus, when a fast optical pulse—or sequence of pulses—interacts with the electrons in an atom, it creates an interference pattern that can effectively image the electron over time.

The challenge is to create a sequence, or ‘train’, of pulses, each with the same, well-defined wavelike properties. For this reason, the technique developed by Yasuo Nabekawa and colleagues at the RIKEN Advanced Science Institute in Wako allows them to compare consecutive pulses in an attosecond light pulse series1.

“Ultimately, the goal of our research is to control atoms and molecules with the attosecond pulse train,” says Nabekawa.

To produce the attosecond pulses, the team started with a series of intense laser-generated ultraviolet light pulses, each approximately 40 femtoseconds in duration. When the laser pulses interacted with a gas of xenon atoms, they generated pulses of light with odd integer (1, 3, 5, etc…) multiples of the frequency of the original laser pulse. These higher frequency pulses—or, ‘harmonics’—reached into the attosecond range.

Detecting ultrafast motion in atoms and molecules requires that the pulses in the train are ‘coherent’ with each other, meaning they are in phase, similar to soldiers marching in lock-step. The team therefore designed its experiment specifically to determine the coherence between the pulses in each of the higher harmonics.

Spatially separating the harmonics allowed the team to measure the coherence between pulses of each harmonic individually. Each harmonic was then split into two beams that traveled down a long arm, before being recombined (Fig. 1). A CCD camera measured the interference pattern between the recombined beams, which provides a measure of the coherence between pulses.

While the current measurements relate to characterizing the optical pulse itself, the RIKEN team plans to build upon these experiments to study ionization and dissociation of electrons from atoms and molecules.

Reference

1. Nabekawa, Y., Shimizu, T., Furukawa,Y., Takahashi, E.J. & Midorikawa, K. Interferometry of attosecond pulse trains in the extreme ultraviolet wavelength region. Physical Review Letters 102, 213904 (2009).

The corresponding author for this highlight is based at the RIKEN Intense Attosecond Pulse Research Team

Saeko Okada | Research asia research news
Further information:
http://www.researchsea.com
http://www.rikenresearch.riken.jp/research/745/

More articles from Power and Electrical Engineering:

nachricht Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht Researchers develop environmentally friendly soy air filter
16.01.2017 | Washington State University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>