Insights on the Excited State Electronic Structures of Ruthenium(II) Polypyridine Complexes Obtained by Step-Scan Fourier Transform Infrared Absorption Difference Time-Resolved Spectroscopy

Step-scan Fourier transform infrared absorption difference time-resolved spectroscopy (S2FT-IR ΔA TRS) was used to study electronic structure in MLCT excited states of [Ru(bpy)2(4-COOEt-4‘-CH3bpy)]2+ and [Ru(bpy)2(4,4‘-(COOEt)2bpy)]2+. Detailed insight on the excited state electronic structure was obtained by comparing the transient ΔA spectra of the MLCT states in the region of ν̄(CO) of the ester group to those of the one-electron-oxidized and -reduced forms of the complexes. ΔA data were collected with 10 ns time resolution.