Visualizing the Geometry of Hydrogen Dimers

The
simplest molecular dimer, H2-H2, poses
a challenge to both experiment and theory as a system with a multidimensional
energy surface that supports only a single weakly bound quantum state.
Here, we provide a direct experimental image of the structure of hydrogen
dimers [(H2)2, H2-D2,
and (D2)2] obtained via femtosecond laser-induced
Coulomb explosion imaging. Our results indicate that hydrogen dimers
are not restricted to a particular geometry but rather occur as a
mixture of all possible configurations. The measured intermolecular
distance distributions were used to deduce the isotropic intermolecular
potential as well as the binding energies of the dimers.