Subscribe free to our newsletters via your
. 24/7 Space News .




TIME AND SPACE
Study details laser pulse effects on behavior of electrons
by Staff Writers
Lincoln NE (SPX) Nov 27, 2014


Jean Marcel Ngoro Djiokap (left) and Anthony Starace. Image courtesy Scott Schrage and University Communications.

By solving a six-dimensional equation that had previously stymied researchers, University of Nebraska-Lincoln physicists have pinpointed the characteristics of a laser pulse that yields electron behavior they can predict and essentially control.

It's long been known that laser pulses of sufficient intensity can produce enough energy to eject electrons from their ultrafast orbits around an atom, causing ionization.

An international team led by the UNL researchers has demonstrated that the angles at which two electrons launch from a helium atom can depend on whether a laser pulse's electric field is right- or left-handed -- that is, whether it rotates clockwise or counterclockwise. The researchers have also calculated the distinct range of angles at which the electrons depart under both conditions.

The authors further confirmed that this effect, which they have coined "nonlinear dichroism," appears only when an atom is struck by a sufficiently short, intense pulse featuring an elliptically shaped electric field.

The study, published in the journal Physical Review Letters, specifically determined that pulses capable of producing this effect last no longer than 200 attoseconds. Counting to one second by intervals of 200 attoseconds per second would take roughly 158.5 million years -- longer than the span that has passed since the end of Earth's Jurassic period.

"The goal in laser atomic physics is to control electron motion and also image it," said Anthony Starace, a George Holmes University Professor of physics who co-authored the study. "To do that, one needs probes that are much faster than the time scale on which electrons move."

However, Starace noted that the exceptionally short duration of attosecond laser pulses -- and the resulting quantum-scale interactions -- can obscure the mechanics underlying laboratory outcomes.

"When things happen on such fast time scales, experimentalists don't always know what they've achieved," he said. "They cannot 'see' how electrons make atomic and molecular transitions. So they need means to ascertain, 'How did we do that?' or, 'What did we have there?'"

The team's paper, Starace said, should help laser physicists address this fundamental and prevalent issue.

"This has applications for timing electron processes," Starace said. "On our human time scale, we think in terms of minutes, but these phenomena take place over inconceivably short fractions of a second. The question is: Are they 10 attoseconds? One hundred? A thousand? No one knows. With these results, we can explore theoretically -- and fairly exactly -- the question of how long electron transitions and processes take."

By identifying and measuring nonlinear dichroism, Starace said, the team's study also offers a new signature that quantum physicists can use to classify experimentally produced laser pulses and verify their results.

"If the experimentalists measure this new effect, they will have information as to how long their pulses are, what polarization their pulses have, and what the shape of their electric field is," Starace said.

"These are means to characterize their pulses."

According to Starace, the study represents a significant step toward an even larger goal of laser physics: manipulating the most fundamental components of matter in the known universe.

"If experimentalists can finally produce such pulses reliably, this new effect allows great control over the way electrons move," Starace said. "If we hit a target with the short attosecond pulses that have a particular duration and polarization, we can tell the electrons whether to go one way or another. This is humankind's dream of controlling electrons, rather than just watching them."

Jean Marcel Ngoko Djiokap, research assistant professor of physics, laid the path to the team's findings by programming the first code capable of accounting both for the interactions between two laser-influenced electrons and the complexity of electric fields that move in multiple dimensions.

"Normally, theorists assume an electric field oscillates in one direction only, which reduces the scale of the computation," Starace said.

"With elliptical polarization, the electric field sweeps around in a plane. This adds another dimension to the problem, which greatly increases the numerical complexity and the difficulty of doing the calculation. Marcel has solved this problem."

Starace likened the team's computational approach to climbing aboard the elliptical "merry-go-round" of the laser pulse's electric field. Performing calculations from this perspective -- rather than the stationary perspective of those watching from outside -- ultimately streamlined the problem, he said.

"If you're on a merry-go-round, people on the sidelines see you spinning around -- but to you, the horse you're sitting on is stationary," Starace said. "What Marcel has done is move the calculation from the laboratory frame (of reference) to this rotating frame, so that all we see is linearly polarized, one-dimensional light. The whole thing becomes simpler."

Starace and Ngoko Djiokap co-authored the study with colleagues from Russia's Voronezh State University; the Laboratory for Laser Energetics at the University of Rochester (N.Y.); and Denmark's Aarhus University.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Nebraska-Lincoln
Understanding Time and Space






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TIME AND SPACE
Researchers Advance 'Quantum Teleportation'
Pasadena CA (JPL) Nov 21, 2014
The world at the quantum level, at the scale of particles too small for the eye to see, is very strange. It's possible, for instance, to have two particles that are "entangled" - that is, they function as if they were connected, even if they are many miles away from each other. New research co-authored by Francesco Marsili, microdevices engineer at NASA's Jet Propulsion Laboratory, Pasade ... read more


TIME AND SPACE
U.K. group to crowd-source funding for moon mission

After Mars, India space chief aims for the moon

China examines the three stages of lunar test run

China gears up for lunar mission after round-trip success

TIME AND SPACE
Second Time Through, Mars Rover Examines Chosen Rocks

Mars was warm enough for flowing water, but only briefly

Several Drives Push Opportunity Over 41-Kilometer Mark

Lockheed Martin Begins Final Assembly Of Next Mars Lander

TIME AND SPACE
Astronauts to get 'ISSpresso' coffee machine

Tencent looks to the final travel frontier

ESA Commissions Airbus As contractor For Orion Service Module

Study Investigates How Men and Women Adapt Differently to Spaceflight

TIME AND SPACE
China expects to introduce space law around 2020

China launches new remote sensing satellite

China publishes Earth, Moon photos taken by lunar orbiter

China plans to launch about 120 applied satellites

TIME AND SPACE
Italy's first female astronaut heads to ISS in Russian craft

Space station gets zero-gravity 3-D printer

NASA Commercial Crew Partners Continue System Advancements

Europe's 3D printer set for ISS

TIME AND SPACE
Soyuz Installed at Baikonur, Expected to Launch Wednesday

Time-lapse video shows Orion's move to Cape Canaveral launch pad

SpaceX chief Musk confirms Internet satellite plan

Orbital recommits to NASA Commercial program and Antares

TIME AND SPACE
Follow the Dust to Find Planets

NASA's TESS mission cleared for next development phase

ADS primes ESA's CHEOPS to detect and classify exoplanets

NASA's TESS Mission Cleared for Next Development Phase

TIME AND SPACE
Swedish military gets upgraded radar facilityw/lll

Boeing Stacks Two Satellites to Launch as a Pair

Eurofighter unveils 1.0-billion-euro radar upgrade

An efficient method to measure residual stress in 3D printed parts




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.