Unveiling New Possibilities: Positron-Ion Crystal Interactions Explored
In a groundbreaking exploration, a research team, including Professor Yasuyuki Nagashima from Tokyo University of Science (TUS), Japan, has opened a new avenue for investigating the interactions between positrons and ionic crystals.
Their collaborative efforts, documented in Physical Review Letters, feature the contributions of Dr. Takayuki Tachibana, a former Assistant Professor at TUS, currently affiliated with Rikkyo University, and Mr. Daiki Hoshi, a graduate student at TUS.
Shining Light on Electron-Stimulated Desorption
The researchers embarked on their journey inspired by the well-established phenomenon known as “electron-stimulated desorption.” This phenomenon involves the ejection of monoatomic positive ions from a solid surface when bombarded by an electron beam.
Dr. Tachibana elaborates, “It has long been known that when electrons are injected into a solid surface, atoms that make up the surface are ejected as monoatomic positive ions.” This led the team to inquire about the outcome of bombarding a crystal with positrons.
Controlled Experiments on Lithium Fluoride Crystals
The team conducted experiments by directing either a positron or electron beam onto the (110) surface of a lithium fluoride (LiF) crystal. They harnessed strategically positioned electric fields generated by deflectors to regulate the incident energies of these charged particles.
These deflectors also played a crucial role in redirecting any desorbed ions from the crystal toward an ion detector. Subsequent spectroscopic analysis of the detected signals unveiled the precise composition of the desorbed ions.
Unveiling Novel Findings
While electrons bombarded the LiF crystal, the expected monoatomic ions, Li+, F+, and H+ (attributable to residual gases in the experimental chamber), were detected.
However, the injection of positrons resulted in the detection of positive molecular fluorine ions (F2+) and positive hydrogen fluoride ions (FH+). Notably, this marks the first documented instance of molecular ions being ejected upon positron irradiation.
Unveiling the Mechanism
After in-depth analysis and further experimentation, the researchers formulated a desorption model to elucidate their findings. According to this model, as positrons infiltrate a solid, some return to the surface after losing energy.
In the case of LiF crystals, these positrons may attract two neighboring fluorine negative ions on the surface, forming a positronic compound. If the bound positron annihilates with one of the fluorine ion’s core electrons, an Auger electron is emitted, leading to a charge swap and the generation of a positive F2+ molecular ion. Repulsing forces from the nearby Li+ ions propel this ion out of the crystal.
Paving the Way for New Possibilities
This study’s findings have the potential to enhance our comprehension of matter-antimatter interactions significantly.
Dr. Tachibana remarks, “The stability and binding properties of positronic compounds provide unique perspectives on the interaction of antiparticles with ordinary substances, paving the way for novel investigations in the field of quantum chemistry.” Moreover, the proposed method could lead to new molecular ions and molecules, opening new avenues for future research.
Expanding Applications
Notably, this approach holds the promise of application in various fields. In materials science, it could facilitate surface modification and the precise study of material properties.
Potential applications extend to cancer therapy, quantum computing, energy storage, and the development of next-generation electronic devices.
Read the original article on Sciencedaily.
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