Stark and Zeeman effects in the lowest excited states of [Zn(bpy) 3](ClO 4) 2:Ru(II). Localized triplet metal-to-ligand charge transfer transitions

• Published in: Journal of luminescence 1994-10, Vol.62 (3), p.123-137
• Main Authors: Riesen, H., Rae, A.D., Krausz, E.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Level splitting and interactions; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect; Spin-orbit coupling, zeeman, stark, and strain splitting, jahn-teller effect
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/0022-2313(94)90339-5

Polarized absorption spectra of the metal-to-ligand charge transfer (MLCT) transitions in the title system are reported. Strong linear dichroisms are observed in accord with the crystal structure which shows that only two of the bpy ligands are crystallographically equivalent. The MLCT transitions to the third ligand are found to lie several hundred wavenumbers higher in energy. A strong angular dependence of the Zeeman effect in luminescence is observed when varying the direction of the magnetic field in the metal-ligand plane. These patterns are quantitatively analyzed in terms of localized transitions. The three lowest-excited electronic states are well described as the components of an orbitally non-degenerate spin triplet state with a very large zero field splitting. All three lowest-energy origins show the same large splitting in an applied electric field, confirming their charge-transfer nature. Luminescence and excitation line narrowing experiments establish that the splitting is a pseudo-Stark effect. Stark-swept transient hole-burning experiments provide a homogeneous line width of ≈ 15 MHz for the origin II in [Zn(bpy) 3](CIO 4) 2:Ru(II) at 1.8 K.