The chemistry of photosynthesis is not fully understood. But researchers from Johannes Gutenberg University Mainz (JGU) in Germany and Rice University in Houston have now uncovered a major piece of the photosynthesis puzzle. Their study has been published recently in Science Advances.
Bushes, trees and other plants are efficient in converting carbon dioxide and water into glucose, a type of sugar and oxygen, through photosynthesis. Knowing the fundamental physical mechanisms that are included and using them for other applications would give huge benefits for all of us. The energy of sunlight could be used to make hydrogen from water, and it could be used as fuel for automobile as an example. Using light-driven processes in photosynthesis in chemical reactions is called photocatalysis.
Scientists use metallic nanoparticles to harness and capture light for chemical processes. Exposing these nanoparticles to light by the process of photocatalysis create plasmons. Plasmons are a collection of oscillations of free electrons found in the material.
"Plasmons act like antennas for visible light," explained Professor Carsten Sönnichsen of Mainz University.
However, the whole physical processes that are involved in photocatalysis involving nano-antennas are yet to be studied and understood in detail. The researchers at Rice University and JGU have now shed some light on this matter.
Graduate student Benjamin Förster and his supervisor Carsten Sönnichsen have been studying this process more extensively. Förster primarily concentrated on knowing how illuminated plasmons reflect light and at what intensity.
His technique needed two particular thiol isomers, molecules that have structures that are arranged as a cage of carbon atoms. Within the structure of the molecules that is cage-like are two boron atoms. By changing the positions of the boron atoms in the two isomers, the researchers were able to study and record the dipole moments, these are the spatial charge separation over the cages in the molecules.
This then led to the discovery of the researchers, that if they applied two types of cages to the surface of the metal nanoparticles and excited the plasmons using light, the plasmons can reflect different amounts of light depending on which cage was on the surface at that time.
In conclusion, the chemical nature of the molecules found on the surface of the gold nanoparticles showed the local resonance of the plasmons because the molecules also change the electronic structure of the gold nanoparticles. The researchers are now focusing on the process of photocatalysis for their future studies.
