2016 Volume 67 Pages 75-79
In this topic, we introduce some previous researches on metal complexes using electroabsorption (Stark) spectroscopy. It measures the effect of an applied electric field on an absorption spectrum (Stark effect). In the analytical process, we can utilize Liptay equation, which contains three terms involving the 0th, 1st, and 2nd order derivatives of the steady-state absorption spectrum, respectively. Meaningful physical quantities such as Δα(the change in polarizability upon photoexcitation) and Δμ(the change in dipole-moment upon photoexcitation) can be calculated by fitting electroabsorption spectrum to the equation. Concerning the assignment of electronic transitions, when an electroabsorption spectrum is dominated by the third term involving the 2nd derivative of the absorption spectrum and Δμ, the observed absorption band should be assigned to charge transfer transition. Thus, as shown in section 4, because the electroabsorption spectrum of [Ru(bpy)3]2+ in visible region resembles, in shape, the 2nd order derivative of the absorption spectrum, these transitions should have a charge transfer character. In addition, we can also describe the Robin-Day classification of mixed-valent multinuclear complexes based on their electroabsorption spectroscopy (see section 5).
