For the first time, physicists used lasers to control reactions at nanometer scale

In cooperation with physicists from the Max Planck Institute of Quantum Optics and the University of Munich in Germany and scientists from Stanford University, laser was used for the first time to control the position of photo-induced reaction on the surface of nanoparticles.

Controlling the strong electromagnetic field on nanoparticles is the key to trigger the target molecule reaction on their surface. This control of strong field is realized by laser. Although scientists have observed the formation and fracture of molecular bonds on the surface of nanoparticles induced by laser in the past, nano-optical control of surface reactions has not been achieved. An international team of scientists led by Dr. Boris Bergues and Professor Matthias Kling of the University of Munich (LMU) cooperated with Stanford University and has now filled this gap. For the first time, physicists have used ultrashort laser pulses to determine the position of photo-induced molecular reactions on the surface of isolated silica nanoparticles.

There are many activities on the surface of nanoparticles. Molecules dock, dissolve, and change their positions. All these have promoted chemical reactions, changed substances, and even produced new materials. Electromagnetic fields can help control events in the nano universe. The research team of ultrafast electronics and nano-photonics led by Dr. Boris Bergues and Professor Matthias Kling has now proved this point. To this end, researchers use powerful femtosecond laser pulses to generate local fields on the surface of isolated nanoparticles.

Using the so-called reactive nano-mirror, a new technology recently developed by the same group, physicists can image the reaction site on the surface of silica nanoparticles and the birthplace of molecular fragments - with a resolution better than 20 nm. By superposing two laser pulse fields of different colors and controlling the waveform and polarization, scientists have achieved nanoscale spatial control, even at higher resolution. Therefore, they must set the time delay between two pulses with attosecond accuracy. When interacting with this customized light, the surface of the nanoparticles and the molecules adsorbed there are ionized at the target location, resulting in the molecular dissociation into different fragments.

"Molecular surface reactions on nanoparticles play a fundamental role in nano-catalysis. They may be a key to clean energy production, especially through photocatalytic water separation," explained Matthias Kling. "Our results also pave the way for tracking the photocatalysis reaction on the nano-particles, which not only has the spatial resolution at the nanometer level, but also has the temporal resolution at the femtosecond level." Boris Bergues added: "This will provide a detailed understanding of its dynamic natural spatial and temporal surface processes."

Scientists expect that this promising new method can be applied to many complex and isolated nanostructured materials.

Source: Network