How brightly a molecule emits light depends on its transition dipole moment, but controlling this through atomic-scale changes to the molecule's structure has been out of reach. Using light emission induced by a scanning tunnelling microscope, researchers show that the vertical position of the central metal atom in a phthalocyanine molecule can either suppress or enhance its emission.

Exploiting this, they built a molecular pair that switches between dark, single-molecule-like and coupled states with subradiant and superradiant modes, and a pair in which energy transfer can be turned on or off. The work, with first author Atif Ghafoor, links QMAT's Synthetic Quantum Materials group led by Shawulienu Kezilebieke at the University of Jyväskylä and Jose Lado's Correlated Quantum Materials group at Aalto, with Riku Tuovinen (Jyväskylä) and Wrocław University of Science and Technology.

The preprint has not yet been peer reviewed.

Image: QMAT