Ian Sims, space chemist

Reproducing the chemical reactions that take place in interstellar space in the laboratory and analysing their products is the speciality of Ian Sims, an expert in laboratory astrophysics at the Rennes Institute of Physics. The British researcher, who has been based in France since 2003, has received €2.1 million from the ERC over five years to build a machine capable of deepening our knowledge of this very hostile environment, which experiments have shown to be anything but an inert desert.
Ian Sim - chimiste de l'Espace

We do not (yet) know how to survey interstellar space. However, our telescopes already allow us to make fairly detailed observations of the clouds of gas and particles present between stars. But to understand their chemistry, it is impossible to analyse samples of them.

"Interstellar space is extremely cold. Matter is very scarce and is subject to intense radiation from the stars. This radiation tends to break up any complex molecules that might form, if atoms happen to meet and react with each other," explains Ian Sims.

And yet, even in this very hostile environment, chemical reactions take place that we do not know much about. To study them, the first step is to reproduce the conditions where they take place, starting with the very low temperature.

"One of the challenges is to be able to analyse the different reaction products at the same time, in particular to be able to determine their proportion," says Ian Sims.

Allocation of ERC funding

The CRESUCHIRP project led by Ian Sims has won €2.1 million in ERC funding over 5 years, precisely to build an experimental device capable of determining this proportion of reaction products.

In addition to the machine, the construction of which is estimated to cost 700,000 euros, the ERC funding will allow Ian Sims to be temporarily freed from some of his teaching duties and to recruit doctoral students and post-doctoral fellows on the subject.

"The application was certainly selected on the basis of our previous results and our international collaborations. But the ability of the university's mechanical engineering department to produce some of the unique parts that will make up this machine was also a factor," Ian Sims is pleased to say.

The "chirped pulse": innovation at the heart of the project

To detect the molecules produced by the chemical reactions in the chamber, they must be subjected to a pulse of a very precise frequency. If the frequency is perfectly matched to the molecule, the molecule resonates, and it is this resonance that is detectable. One of the limitations of this technique is that it only allows the detection of one molecule, and therefore one reaction product at a time: these have a very short life span.

Ian Sims will therefore use the chirped pulse technique, which scans a wide range of frequencies continuously in a few hundred nanoseconds. All the molecules sensitive to one or other of the frequencies covered by this scan then resonate, which allows almost simultaneous detection, compatible with the very short life span of the reaction products.

At the end of the project, it is therefore a device that is unique in the world that will be at work on the premises of the Institut de Physique de Rennes.

"Once completed, this machine will enable us to constrain the models of astrophysicists, and thus learn more about what happens between stars, in clouds of interstellar gas and dust, or in the atmospheres of other planets", says Ian Sims.