Posted in | Quantum Physics

Scientists Observe Electrons Liberated from Atoms for the First Time

Scientists have viewed the world through the eye of an electron, but only for a fraction of a second.

This drawing illustrates the path of packets of light waves (blue dashed line, moving right to left), as they hit an atom (white sphere with green nucleus) and an electron is knocked free (purple dashed line, moving left to right). The red laser light waves below serve as a frame of reference, so researchers can observe the momentum of the electron as it gets farther from the atom. CREDIT: Robert Jones, University of Virginia.

This means that for the first time, they have been successful in observing an electron liberated from near an atom when light is absorbed by the atom. Similar to taking “snapshots” of the activity, they were successful in tracking the way in which the distinctive momentum of each electron was altered in the very short time span it was needed to get liberated from its host atom and be a free electron.

In the Nature Physics journal, the Scientists have described that observing electrons in such minute detail is a first step in regulating the behavior of electrons inside matter, and hence the first step toward a long and complex road that can ultimately culminate in the propensity to develop innovative states of matter at one’s discretion.

According to Louis DiMauro, Project Leader and Hagenlocker Chair and Professor of Physics at The Ohio State University, an instant result is that the Scientists will now be able to categorize the quantum mechanical behavior of electrons constituting different atoms.

Now we can look at an electron and decipher its early history. We can ask how is it different if it came from a helium atom or a neon atom, for instance.

Louis DiMauro, Project Leader and Hagenlocker Chair and Professor of Physics, The Ohio State University

However, the eventual aim of the Scientists is to map quantum mechanical systems (which apply to the ultra-small world) on a considerably larger scale such that they can ultimately regulate the movements of sub-atomic particles in a molecule.

If you think of each snapshot we take as a frame in a movie, maybe someday we could stop the movie at one particular frame and change what happens next—say, by poking an electron with light and changing its direction. It would be like going inside a chemical reaction and making the reaction happen in a different way than it would naturally.

Louis DiMauro, Project Leader and Hagenlocker Chair and Professor of Physics, The Ohio State University

Characteristically, DiMauro, Dietrich Kiesewetter—a Physics Doctoral Student—and their collaborators have demonstrated that a well-established laboratory process for analyzing free electrons can be used to investigate electrons that are not so very free but are ready to get liberated from an atom.

When sub-atomic forces of a nucleus and adjacent electrons act on electrons, the electrons act differently, and these forces fade away when the electrons get farther away from an atom. Although the liberation takes less than a femtosecond, that is, one-quadrillionth of a second, this research has demonstrated that the momentum of an electron gets altered a number of times in the process when it loses contact with the individual atomic parts. These changes occur on the scale of attoseconds, that is, quintillionths of a second or thousandths of a femtosecond.

The process adopted by the Researchers is known as Reconstruction of Attosecond Beating By Interfering Two-photon Transitions, or RABBITT, which involves irradiating the gaseous atoms using light to unearth the quantum mechanical information. The procedure has been known for almost 15 years and is a standard technique for analyzing phenomena occurring on extremely short timescales.

However, not all the quantum mechanical information acquired through RABBITT can be used, or at the minimum, until now, not all the information was considered to be usable. Consequently, the researchers have named their version of the process RABBITT+.

We’re using the information that other people would throw away, the part that comes from close to the nucleus of the atom, because the data always seemed too complex to decipher. We developed a model that shows we can extract some simple but important information from the more complex information.

Louis DiMauro, Project Leader and Hagenlocker Chair and Professor of Physics, The Ohio State University

DiMauro has acknowledged the work of Robert Jones, the Francis H. Smith Professor of Physics at the University of Virginia, which involved developing significant elements of the model that rendered the information useful. Ohio State Professor of Physics Pierre Agostini and Former Doctoral Students Stephen Schoun and Antoine Camper, who have since graduated, are other Co-authors of the paper.

The U.S. Department of Energy, Office of Science funded this study.

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