The electronic spectrum of cryogenic ruthenium-tris-bipyridine dications

We present the electronic spectrum of Ru(II)-tris(2,2’-bipyridine), Ru(bpy)$_3^{2+}$, measured by photodissociation spectroscopy of mass selected Ru(bpy)$_3^{2+}\cdot$N$_2$ ions prepared in a cryogenic quadrupole ion trap. The spectrum is composed of several metal-to-ligand charge transfer (MLCT) transitions, as well as metal centered bands and ligand centered $\pi \pi^$ states. We observe several partially resolved electronic transitions in the MLCT band. We discuss the results in the framework of time-dependent density functional theory