Spectroscopic and magnetic evidence for multiple-state emission from tris(2,2′-bipyridine) ruthenium (II) sulfate

Spectral changes of the charge-transfer photoluminescence of the title compound between 2 and 10°K have been interpreted in terms of a manifold of emitting states in thermal equilibrium. Analysis of the band shape changes by means of the Boltzmann law yields an energy gap of 10.2 cm^?1 in excellent agreement with the value obtained from published decay time measurements. A 75-kG magnetic field on the sample maintained at 1.65°K switches the emission back to that seen at 4.2°K. These results also corroborate the assignment of the lowest two states responsible for the luminescence to A₁ and E symmetry in the group D₃.