Cold collisions catalyse conformational conversion

Abstract

We have determined the abundance of two different conformational structures of the mixed benzene dimer (C₆H₆)(C₆D₆) in a molecular beam, with various carrier gases. These two T-shaped conformers have a subtle zero-point energy difference of only a few cm⁻¹, and a transition state barrier of about 64 cm⁻¹. Nevertheless, depending on the carrier gas, the lowest energy conformer can exclusively be prepared in the molecular beam. Low-energy two-body collisions of the benzene-dimers with the carrier gas atoms are concluded to be responsible for this.