Elementary particles such as electrons also behave as waves. An electron has a wave function which charts the probability of the electron being located in a particular position in 3-D space. It is possible for particular interference patterns generated by colliding laser beams to affect electrons via interaction with their wave function.
In February of this year, there were experiments where the excitation of an atomic nucleus via the absorption of an electron was observed. This is called the NEEC effect which stands for “nuclear excitation by electron capture”. It had been theorized to exist over forty years ago but had never been seen.
Electrons are usually though to obit far out from the nuclear of the atom but it turns out that the electron wave function indicates that there is a possibility that electrons could actually be in the nucleus. A free electron can be absorbed by a hole in a normally filled electron shell. If the kinetic energy and the binding energy of the free electron exactly match the difference between two nuclear states, then nuclear excitation can occur.
Researchers at the Swiss Federal Institute of Technology have just reported on a new process for exciting and controlling the energy inside an atomic nucleus as explained by the NEEC effect. They have achieved a more precise control of electrons by light than was possible in the past by coherent manipulation of free-electron wave function at an attosecond (An attosecond is 1×10−18 of a second or one quintillionth of a second) timescale. It is possible that they may be able to accomplish a similar level of control at a zeptosecond (An zeptosecond is 1×10−21 of a second or one sextillionth of a second) timescale.
In order to control the electron, the researchers created an interaction between a free-electron wave function. (A free electron is not attached to an atom or ion or molecule and it is free to move under the influence of an electric field.) (A wave function mathematically describes the wave characteristics of a particle.) and a light field created by the intersection of two tiny pulse of intense laser light. The amplitude and phase of the resulting electron wave function was measured with ultrafast electron spectroscopy. This breakthrough could possibility be developed into a way to release and harvest the energy inside an atomic nucleus. This would pave the way for more efficient nuclear technologies.
A press release from the researchers said, “This breakthrough could allow physicists to increase the energy yield of nuclear reactions using coherent control methods, which relies on the manipulation of quantum interference effects with lasers and which has already advanced fields like spectroscopy, quantum information processing, and laser cooling."
The process developed by the Swiss researchers may inspire the next generation of nuclear energy-harvesting systems.
One of the researchers remarked that “Ideally, one would like to induce instabilities in an otherwise stable or metastable nucleus to prompt energy-producing decays, or to generate radiation. However, accessing nuclei is difficult and energetically costly because of the protective shell of electrons surrounding it.”