Figure 3.

Spectroscopic pump–probe results from the photoexcited spin transition of [Fe^II(bpy)₃]²⁺ in solution. After excitation into the MLCT state, transition into the HS ⁵T₂ state [inset (c)] causes an increase of the Fe-to-ligand distance [inset (a)]. This structural change is tracked by the XANES trace at 7125 eV [(a), black symbols, vertically offset by 0.5]. The structural HS rise has been fitted by an exponential rise of 162 ± 6 fs (Lemke et al., 2013 ▶). (b) Time-dependent Kβ emission difference spectra. The transient traces at 7061 eV and 7054 eV have been extracted [(a) green diamond symbols and (c) black symbols, respectively]. The data have been overlaid with results from global fits including (blue lines) and excluding (green dashed lines) population of and intermediate ³T triplet state (Zhang et al., 2014 ▶). [Reprinted by permission from Macmillan Publishers Ltd: Zhang et al. (2014) ▶. Nature (London), 509, 345–348, copyright (2014).]