Fig. 4. Transient IR absorption tracks the appearance of the singly reduced species. (A) Differential absorption (pump on – pump off) of Re(bpy)(CO)3Cl in 20% TEOA/THF solution in the carbonyl stretching band (inset), and zoomed to the region around 1996 cm–1, corresponding to the singly reduced species. (B) Double-difference spectra at various time delays between the 400 nm pump and mid-IR probe showing the growth of the band. (C) Integrated singly-reduced band indicates a growth on a ∼70 ps time scale, which is significantly faster than expected by diffusion. The standard deviations of the double difference signals in (B) are in the range of 1.5–3.6 × 10–5 OD.
