In a new approach to scintillation, scientists are looking beyond the composition and intrinsic properties of the material to examine its surrounding environment and the way it interacts with light. Dr. Dominik Kowal and Dr. Michał Makowski of the Photonic Materials Research Group are investigating these phenomena at the nanoscale, at the intersection of photonics, plasmonics, and materials engineering. Their work could open up new possibilities for designing more efficient scintillators with precisely controlled properties.
From Material Composition to Designing Its Environment
For years, scintillator research focused primarily on finding new chemical compositions, synthesis methods, and ways to produce ever better crystals—materials capable of efficiently absorbing ionizing radiation and then emitting light rapidly and intensely. As Dr. Dominik Kowal explains, however, this approach faces limitations imposed by the properties of the material itself. In the search for new ways to improve scintillation performance, scientists are therefore increasingly turning to the nanoscale. This makes it possible to bring quantum effects and light–matter interactions to the forefront.
“This is an entirely new field of research, rooted in photonics and plasmonics, while also overlapping with the physical chemistry of these materials,” says Dr. Kowal.
One of the key directions of his research is controlling the emitter’s immediate environment. The same nanoscintillator can behave differently when isolated than when placed near carefully designed plasmonic nanostructures. Among the properties that can change are the rate and intensity of its emission.The nanoscale offers particularly interesting opportunities. When an emitter is only a few nanometers in size, quantum effects become pronounced, and its properties can differ significantly from those of a bulk crystal.
“At the nanoscale, properly matching the dimensions of the individual components is also important because it strengthens their mutual interaction,” Dr. Kowal explains.
Nanostructures and Light–Matter Interactions
Dr. Michał Makowski is pursuing this approach experimentally. In earlier studies, the team showed that combining a nanoscintillator with silver nanocubes can modify its emission. The next step was to determine whether this effect could be enhanced even further. The researchers varied the size of the silver nanocubes while also introducing a different type of emitter with more strongly directional emission. The goal was not only to increase the amount of emitted light, but also to gain greater control over how that light is emitted. As a result, the researchers were able to move from the weak- to the strong-coupling regime of light–matter interaction.
“The Purcell effect operates in the weak light–matter coupling regime. You could say that the emitter and the nanoparticle ‘see’ each other, but they are like two people sitting on opposite sides of a table—they can wave to each other. If we modify both the emitter and the nanoparticle appropriately, however, that table starts to get smaller. At some point, we can shake hands. That is when we move into the strong light–matter coupling regime,” Dr. Michał Makowski explains.
In the strong-coupling regime, the situation changes qualitatively. It is no longer simply a matter of faster or more intense emission. New hybrid states—polaritons—are formed, and the emission spectrum itself also changes. This gives researchers an additional way to control the properties of the system. Tailoring the spectral characteristics of the emission could, for example, help match a scintillator more effectively to a particular detector whose sensitivity depends on the wavelength of light.
Strong Light–Matter Coupling in Scintillators
Of particular significance is the fact that the effect was achieved under high-energy radiation excitation. As Dr. Michał Makowski points out, this is the first such observation. At the same time, it raises the question of whether the mechanism of strong coupling operates in the same way under these conditions as it does under conventional optical excitation.The team does not yet have enough data to answer that question conclusively. Determining the answer has now become one of the next research challenges and a direction for further study.
“This may indicate that we are touching on a new branch of physics,” says Dr. Makowski.
New Opportunities in Imaging and Radiation Detection
The research also has application potential. One possible direction is the development of imaging systems that use high-energy radiation. More efficient and faster scintillators could eventually enable more detailed imaging in positron emission tomography (PET) and X-ray diagnostics. Greater detection sensitivity could also make it possible to obtain useful images at lower radiation doses.
Other possibilities arise from controlling the emission spectrum and decay time. Not all applications of the effects observed today are yet known, but the ability to control additional scintillation parameters opens the way to developing new types of detectors, imaging methods, and technologies based on high-energy radiation.
Nanophotonics at Łukasiewicz – PORT
This type of research brings together expertise in chemistry, materials engineering, nanotechnology, and photonics. At the Wrocław-based institute, scientists can produce nanoparticles using chemical synthesis methods, combine them with nanoscintillators to form composites, and fabricate ordered structures using lithographic techniques.
The researchers also present their findings and emerging research directions in leading scientific journals.
Dr. Dominik Kowal, together with Prof. Charles Roques-Carmes of the Institute of Science and Technology Austria (ISTA) and Prof. Liang Jie Wong of Nanyang Technological University (NTU) in Singapore, co-authored the review article “Quantum and Nanophotonic Perspectives on Light–Matter Interaction in Scintillation,” published in Energy Material Advances. The review organizes the current state of knowledge on the use of quantum phenomena and nanophotonics in scintillation and identifies possible directions for the field’s future development.
Dr. Michał Makowski is the first author of “Strong Coupling in Bulk Nanoplasmonic Nanoplatelet Perovskite Scintillators,” published in Advanced Materials. The authors present experimental results on nanoplasmonic perovskite scintillators and strong light–matter coupling.
The two publications highlight complementary aspects of research carried out by the Photonic Materials Research Group: a broader perspective on the development of scintillation through quantum phenomena and nanophotonics, and experimental efforts to find new ways of controlling light–matter interactions.
