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.
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
A paper battery powered by bacteria
21.08.2018 | American Chemical Society
Converting wind power for storage purposes
21.08.2018 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Power and Electrical Engineering
21.08.2018 | Life Sciences
21.08.2018 | Medical Engineering