Featured Research

from universities, journals, and other organizations

Can One 'Pin Down' Electrons?

Date:
May 19, 2008
Source:
Goethe University Frankfurt
Summary:
Experiments by physicists end a long-lasting dispute with an answer that apparently satisfies everyone. When atoms form molecules, they share their outer electrons and this creates a negatively charged cloud. Here, electrons buzz around between the two positively charged nuclei, making it impossible to tell which nucleus they belong to. They are delocalized. But is this also true for the electrons located closer to the nucleus?

What was the initial location of the electron before it was ejected from the dumbbell-shaped nitrogen molecule by a high-energy photon (blue)? The diagram shows the probability distribution of the photo-electron in the case of its prior localization (left), or for the Auger electron (right). As both electrons form an entangled state, the Auger electron is also localized.
Credit: Markus Schoeffler

When atoms form molecules, they share their outer electrons and this creates a negatively charged cloud. Here, electrons buzz around between the two positively charged nuclei, making it impossible to tell which nucleus they belong to. They are delocalized.

But is this also true for the electrons located closer to the nucleus? And are those electrons spread out too, or do they belong to just one nucleus, i.e. are they localized? These questions, that scientists have hotly disputed over the last 50 years, have now been answered by an international team of scientists, led by Frankfurt University's atomic physics group. Their discoveries are reconciliatory. As is so often the case in quantum theory, there is no single 'right' answer -- one solution is just as valid as the other.

In order to answer these questions, the scientists first removed the innermost electron located close to the nucleus from nitrogen molecules (N2), using high-energy light from a synchrotron radiation source at the Advanced Light Source at the Lawrence Berkeley National Laboratory, Berkeley, California. It is reasonable to assume that these photo-electrons belong to one nucleus and can thus be located. They leave behind a vacancy in the inner core shell, which is then filled by an outer electron.

Additionally a second electron (an Auger electron) is ejected from the molecule. This Auger electron acts as a probe that can determine exactly where the original hole was created. Both electrons, the photo-electron and the Auger electron, form an entangled state, which means that as soon as one is measured, the properties of the second are determined as well. This prediction of quantum theory - which was rejected by Einstein as a "spooky long-range interaction" - has since been found to be valid for twin photons. It is the basic scheme behind quantum cryptography as well as "Quantum teleportation".

Professor Reinhardt Dφrner's group is the first to prove the existence of such entangled states for electrons, using the COLTRIMS technology, which has been developed in Frankfurt over the last decade. With this experimental set-up, they are able to reveal the pathways of the two electrons created. In the current issue of the journal Science, the physicists claim that the question of whether an electron is localized or not can only be answered for the complete system.

If the innermost electron is localized, the second electron can be assigned to either of the two nuclei. But sometimes it proves impossible to determine whether the first electron originates from the left or the right 'atom of the first electron. In this case the second electron is also delocalized.

With these experimental details, it is now possible to explain the observations of the last 50 years in a unified model. Both groups - those supporting the localized theory and those endorsing a delocalized picture - are thus reconciled. Dr. Markus Schφffler, who is responsible for the measurement, sees further exciting perspectives opening up and he plans to continue his work on this topic in Berkeley, funded by a scholarship from the Alexander von Humboldt Foundation.


Story Source:

The above story is based on materials provided by Goethe University Frankfurt. Note: Materials may be edited for content and length.


Cite This Page:

Goethe University Frankfurt. "Can One 'Pin Down' Electrons?." ScienceDaily. ScienceDaily, 19 May 2008. <www.sciencedaily.com/releases/2008/05/080515145358.htm>.
Goethe University Frankfurt. (2008, May 19). Can One 'Pin Down' Electrons?. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2008/05/080515145358.htm
Goethe University Frankfurt. "Can One 'Pin Down' Electrons?." ScienceDaily. www.sciencedaily.com/releases/2008/05/080515145358.htm (accessed July 26, 2014).

Share This




More Matter & Energy News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) — Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) — When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins