Interesting Effects Of Light On Small Molecules On Earth And In Space

ScienceDaily (May 25, 2008) Dutch researcher Mark van der Loo has investigated the influence of light on the behaviour of small molecules and has calculated the effect of light for several types of molecules. His theoretical research into light-induced processes in the hydroxyl radical (OH), the hydrogen molecule (H2) and nitrous oxide (N2O) has directly contributed to a better understanding of chemical processes taking place on Earth as well as in the universe.

The interaction between light and matter is vitally important for a wide range of applications, such as the modelling of chemical processes in the Earth's atmosphere, research into combustion processes and the measurement and modelling of processes in astrophysics. Under the influence of light, molecules can vibrate, rotate, disintegrate or even be formed out of individual atoms. These processes take place according to the laws of quantum mechanics. Although the basic equations are known, solving them is a considerable technical problem. Thanks to Van der Loo's research, such solutions are a step closer.

Hydroxyl radical

The hydroxyl radical (OH) is highly reactive and plays an important role during combustion processes and chemical processes in the Earth's atmosphere. Van der Loo carried out calculations on OH, which examined the light absorption followed by decay and/or disassociation of the molecule. The lifespan of OH in atmospheric molecules is now no longer an uncertain factor.

Hydrogen molecules

Hydrogen molecules (H2) played an important role during the formation of the very first stars. The researcher investigated the contribution of the Raman association process to the formation of H2. In this process, individual colliding hydrogen atoms form hydrogen molecules under the influence of cosmic background radiation. Van der Loo was the first to completely describe this process from a quantum mechanics viewpoint and to accurately calculate it. His conclusion is that the process made an important contribution to the universe when it was about 10,000 years old, whereas the total contribution up until about 100 million years after the Big Bang is small.

Nitrous oxide

Nitrous oxide (N2O), laughing gas, is one of the greenhouse gases in the Earth's atmosphere. It can decompose in the atmosphere (photodissociation), into N2 and O, under the influence of sunlight. In the laboratory, photodissociation experiments can be performed to investigate the interaction between N2 and O at a fundamental level. Recently, a relatively simple mathematical model was used to interpret such an experiment on N2O. This model is based on the known N2O interaction at large distances between the fragments. In his PhD thesis, Van de Loo examines whether the assumptions underlying this model are valid and he draws the provisional conclusion that this is only partly justified.

Van der Loo's doctoral research was funded by the NWO programme Jonge Chemici (Young Chemists).