Light and Matter

Photo: Light and Matter

Is this what the energy source of the future will look like? Specially synthesized molecules split water into its components, hydrogen and oxygen, with the help of sunlight. The plan is for this process, which occurs in nature as “photosynthesis”, to be replicated in the laboratory to free the world from its dependency on fossil fuels. This artificial photosynthesis should supply mankind with a virtually inexhaustible and clean energy carrier.

Unfortunately, the dream of artificial photosynthesis as an energy supplier on a grand scale is still a long way off becoming a reality. Scientists have yet to acquire the necessary knowledge concerning the fundamental processes inside potential hydrogen producers. However, a new research group at the University of Würzburg is about to start work on this, bringing together scientists from various branches of physics and chemistry. Its spokesman is Professor Tobias Brixner, Chairman of the Department of Physical Chemistry.

Molecular aggregates and their reactions to light will be the main focus of the Würzburg research group. “We will examine the interaction between light and matter with a view to understanding and controlling the dynamic processes and optical phenomena,” says Brixner. It is hoped that their findings will enable the scientists to customize new materials with specific properties.

Of course, facilitating the breakthrough of artificial photosynthesis will be just one of the goals with these new materials. Extremely energy-efficient light sources, tap-proof encryption technology, super-fast quantum computers, effective photovoltaic elements, nano-components that can repair themselves: these will all be conceivable once the fundamental processes in the molecular aggregates have been clarified and understood.

Chemists understand molecular aggregates as the smallest building blocks in macroscopic systems such as liquids, solutions, or crystals. Inside these, molecules are arranged in specific structures with strong or weak links binding them. The diverse interactions between the individual blocks determine what happens inside the aggregates when light falls on them.

“What makes molecular aggregates so special and therefore appealing compared, for example, to inorganic solids is the fact that the properties of these molecular ‘basic building blocks’ can be varied deliberately,” explains Brixner. Changes at the microscopic level result in changes on a macroscopic scale as well. Though, the exact processes are still unknown. “In the past, although scientists went to great lengths examining countless molecules optically, there was generally no systematic variation of aggregates,” says Brixner. In many cases, therefore, current knowledge is inadequate for a prediction of the properties of a complex system based on the properties of the underlying molecular building blocks.

This is where the work of the Würzburg research group will begin: the group will spend the next three years closely studying the interactions between light and matter in molecular aggregates. “Once we are familiar with the fundamental rules of the interactions, it should be possible to produce a new generation of materials that exceed those we have today,” states Brixner.

COMPAMED.de; Source: University Würzburg