Photo absorption of cold ionic complexes can be measured utilizing He messenger spectroscopy. The image shows a red laser hitting a sample of phthalocyanine – the structure of the molecule is also shown. This technique also enables to probe the effect of solvation including hydration of biomolecules as a function of the number of solvent molecules.
Laser spectroscopy of cold ions in combination with quantum chemical calculations provides insight into the interaction of molecules with mass selected metal cluster ions. Activation of otherwise inert molecules, such as CH4 or CO2 can be measured as a function of the cluster size which can be considered as a first step for a catalytic reaction. The low binding energy of He taggants is beneficial as absorption of a single IR photon will lead to its loss and can be recorded by mass spectrometry.