Controlling atomic-scale reactions marks a major leap forward

Scientists at the University of Bath have made a significant advance in nanotechnology, unveiling a method to control atomic-level chemical reactions. This achievement is expected to enhance fundamental scientific understanding and improve processes such as drug development.

The ability to control reactions with single-molecule precision has been a goal for researchers worldwide. While previous milestones, such as IBM's manipulation of individual atoms in their atomic-scale movie "A boy and his atom," showcased remarkable precision, directing reactions with competing outcomes has remained a challenge. This new study addresses this limitation.

Enhancing Reaction Efficiency

Chemical reactions often yield multiple outcomes, with only some being useful. For example, in drug synthesis, reactions like cyclisation produce the desired therapeutic compound, while other outcomes, such as polymerisation, result in waste. Precise control over these reactions could streamline processes, improving efficiency and sustainability.

Scanning Tunnelling Microscopy

At the heart of this breakthrough lies scanning tunnelling microscopy (STM), a technology that enables scientists to explore and manipulate materials at the atomic scale. Unlike conventional microscopes, which rely on light, STM uses an atomically fine tip to measure electric current across surfaces, creating highly detailed maps of atomic structures.

This technique can also influence molecular behavior. "STM technology is typically used to position individual atoms or molecules for targeted interactions," explained Dr. Kristina Rusimova, lead researcher. "Our research demonstrates that STM can control reaction outcomes by selectively manipulating charge states and resonances through targeted energy injection."

Controlled Reaction Pathways

The study demonstrated the ability to influence reactions in toluene molecules by injecting electrons through the STM tip. "We found that the ratio of reaction outcomes could be controlled by adjusting the energy of injected electrons," said Dr. Peter Sloan, a senior lecturer at Bath. This precision allowed researchers to favor specific reaction pathways.

PhD student Pieter Keenan elaborated: "By maintaining identical initial conditions and varying only the energy input, we showed how molecular reaction barriers determine outcomes. This effectively lets us 'load the molecular dice,' making one outcome more probable than another."

Future Applications

"This study combines advanced theoretical modeling with experimental precision," added Professor Tillmann Klamroth from Potsdam University. "It provides groundbreaking insights into molecular energy landscapes, paving the way for future innovations in nanotechnology."

Dr. Rusimova emphasized the potential impact: "This advancement brings us closer to programmable molecular systems, with applications in medicine, clean energy, and molecular manufacturing."

Research Report:Measuring competing outcomes of a single-molecule reaction reveals classical Arrhenius chemical kinetics