Step-scan Fourier transform infrared absorption difference time-resolved spectroscopy studies of excited state decay kinetics and electronic structure of low-spin d(6) transition metal polypyridine complexes with 10 nanosecond time resolution

Step-scan Fourier transform absorption difference time-resolved spectroscop y ((SFTIR)-F-2 Delta A TRS) has been used to collect mid-IR time-resolved i nfrared spectra of the transient electronic excited states of polypyridine transition metal complexes with 10 ns time resolution. The time-resolved da ta can be used for kinetic analysis or to generate "snapshots" of the lowes t lying excited state. Shifts of vibrational bands in the excited state rel ative to the ground state can be used to infer significant details of the e lectronic structure of the excited stare. The multiplex advantage of the FT IR technique allows a wide variety of vibrational bands to be analyzed for this purpose. In the example illustrated, the shift of the ester nu(CO) ban d in {Ru(bpy)[4, 4'-(COOEt)(2)bpy](2)}(2+) compared to those ill related co mplexes has been used to address the question of electron delocalization in the excited state.