Spin splitting unconstrained by electron pairing: the spin-vibronic states

Spin splitting of individual vibronic states was observed in a single molecule where all the electrons are paired, as well as a molecule with one extra electron injected. This observation was made possible by the use of a scanning tunneling microscope capable of reaching ～800 mK in a magnetic field up to 9?T and the sharpness of the vibronic states, ～1 meV. These conditions also led to the resolution of spectral diffusion caused by minute fluctuations at the probing location of the molecule.