Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electron flashes for the nanoworld – a new source of ultrashort electron pulses

29.01.2007
Researchers at the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) in Berlin, Germany, have developed a novel source of extremely short electron pulses.

The electron source is based on an ultra-sharp metallic needle illuminated with short light pulses from a laser. “With these electron pulses, it is possible to directly observe fast processes in the nanoworld”, Claus Ropers explains, who performed the work in collaboration with Daniel Solli, Claus-Peter Schulz, Christoph Lienau and Thomas Elsaesser. The researchers report their findings in the present issue of Physical Review Letters (Volume 98, 043907 (2007)).

Nanostructures play a key role in physics, chemistry and materials sciences, and they are at the foundation of modern microelectronics and communication technology. These structures with dimensions of few nanometers – 1 nanometer (nm) is a billionth of a meter – exhibit physical and chemical properties which can be tailored in a wide range.

In order to determine the dimensions and other structural characteristics of nanostructures, researchers often employ powerful electron microscopes. Such instruments only deliver static images of the time averaged state of the sample investigated. The function of nanosystems is, however, often closely related to dynamical processes occuring on time scales of less than one picosecond (1 ps, one millionth of a millionth of a second). Therefore, intense research efforts worldwide are devoted to develop methods capable of imaging such processes, for example as a series of snapshots. Besides ultrashort pulses of light, x-ray and electron pulses are particularly suited for this purpose, as they can provide direct information on rapid structural changes.

The team at the MBI has now demonstrated a new technique to generate ultrashort and localized electron pulses. A metallic needle of only 40 nm diameter is illuminated with laser light pulses of only 0.007 ps duration. The intensity of the incident light is enhanced at the needle tip to an extent that it leads to strong emission of electrons. These charged particles can be used to investigate a sample close to the needle. The particluar excitation conditions result in an extremely short duration of the electron pulses of less than 0.02 ps which determines the temporal resolution of this new “electron camera”.

The potential of this “point-like” electron source for the imaging of nanostructures has been demonstrated in experiments, where the illuminated needle is raster-scanned in close proximity across a 50 nm wide nano-groove in a gold surface. Along the cross-section of the metal groove, the electron yield varies due to the varying generation conditions. This allows for a direct determination of the profile and the electromagnetic field distribution at the groove with nanometer precision. In the same way, microelectronic devices on the nano scale and their properties can be investigated.

Currently, the electron pulses are used in first time-resolved experiments on nanostructures to image ultrafast processes. Beyond the application of the source in the raster scanning scenario, the researchers suggest a broad applicability for electron diffraction experiments with highest temporal resolution on solids, surfaces or molecular systems.

The research has been financially supported by the German Research Foundation.

Josef Zens | alfa
Further information:
http://www.fv-berlin.de

More articles from Physics and Astronomy:

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

InLight study: insights into chemical processes using light

05.12.2016 | Materials Sciences

High-precision magnetic field sensing

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>