TIMS, Diving into the world of atoms

An interview of Bernard BOURDON, Group Leader, Lyon Geology Lab, ENS Lyon

What is a TIMS?

TIMS is an acronym for 'Thermal ionization mass spectrometer'. Mass spectrometry is a method of "destructive" analysis that makes it possible to analyze the atomic masses of the atoms present in a sample. In particular, it makes it possible to measure the relative abundance of isotopes of the same chemical element (e.g. carbon 12, 13 and 14). The term "thermal ionization" refers to this method of analysis. This is a heating technique that causes the evaporation and ionization of the sample, i.e. the transformation of the atoms into ions. This enables them to be accelerated and separated according to their mass, thanks to a very powerful magnet. The principle is relatively simple: the heavier ions are deflected less than the lighter ones, and are therefore not detected in the same place.

What are the applications of such an instrument?

Since mass spectrometry can be applied to all types of samples (mineral, organic, bio-organic), whatever their physical state (solid, liquid or gaseous), it has many applications in biology, chemistry, medicine, geology, the environment, nuclear power, etc.

 In which types of project(s) is it used?

The TIMS instrument, funded by the LabEx LIO, is currently at the Geology Laboratory of Lyon and is used mainly for high precision isotopic analyses.

 When was the moon created?

Researchers at LIO have attempted to determine the age of the moon using lunar rock samples collected by NASA. Remember that the moon was formed following a collision between the Earth and another celestial body. This caused the vaporization, then the aggregation of the matter ejected during the impact. At the time of this collision, rubidium, a radioactive and volatile element, largely disappeared from the rocks thrown into orbit. Today, by measuring the abundance of strontium 87 in the lunar rocks (strontium 87 is called the "son" element of rubidium, formed by the radioactive decomposition of rubidium after a few billion years), it is possible to deduce the moment of impact.

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