A group of scientists from the University of Ottawa has made important progress in their understanding of ionization, a basic physics process that affects several disciplines, such as plasma physics and X-ray creation. The study was published in Nature Communications.
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An atom is the building block of everything. Ionization occurs when ions lose electrons and turn into charged particles. It appears in the Northern Lights, plasma TVs, and lightning. Experts believed that the influence over this mechanism was restricted.
Under the direction of Ph.D. candidate Jean-Luc Begin and Ravi Bhardwaj, Full Professor in the Department of Physics at uOttawa, along with Professors Ebrahim Karimi, Paul Corkum, and Thomas Brabec, the study presents novel techniques for regulating ionization with carefully designed light beams.
In attosecond science and strong field physics, ionization is essential because it explains how electrons break free from their atomic connections. It has long been believed that there are boundaries to how this process can be controlled.
We have demonstrated that by using optical vortex beams—light beams that carry angular momentum—we can precisely control how an electron is ejected from an atom. This discovery opens up new possibilities for enhancing technology in areas such as imaging and particle acceleration.
Ravi Bhardwaj, Full Professor, Department of Physics, University of Ottawa
The study was conducted over two years at the University of Ottawa's Advanced Research Complex. The team discovered that the handedness and characteristics of the optical vortex beams highly influence ionization rates. The scientists accomplished selective ionization by shifting the location of a "null intensity region" inside the beam, launching a brand-new idea known as optical dichroism.
Key Findings From the Research Include:
- The first example of ionization is based on the characteristics of angular momentum-carrying light beams.
- Improved control over ionization processes that might result in more advanced imaging methods.
- A fresh perspective on how light might be designed to affect electron activity in previously unheard-of ways.
This discovery, which expands on fundamental theories in the subject, could entirely change the way scientists handle ionization. It might result in quicker computers, better medical imaging, and more effective study methods—it is not only for physics textbooks. In quantum computing, where individual particle control is essential, it holds particular promise.
Changing the way we think about how electrons are ejected has been challenging, but our research proves that using advanced laser technologies can lead to new discoveries that impact both science and technology.
Ravi Bhardwaj, Full Professor, Department of Physics, University of Ottawa
Journal Reference:
Bégin, J., et al. (2025) Orbital angular momentum control of strong-field ionization in atoms and molecules. Nature Communications. doi.org/10.1038/s41467-025-57618-8