X-ray photochemistry in iron complexes from Fe(0) to Fe(IV) – Can a bug become a feature?

Reversibility of Ferri-/Ferrocyanide Redox during Operando Soft X-ray Spectroscopy

“…Under these conditions, our spectra compare well with those reported previously for powders of ferri-and ferrocyanide ( Figure S6) in the absence of photo-damage, 22,39,[43][44][45][46] as well as ferrocyanide solution. 19 We cannot confirm the discrepancies between powders and concentrated solution of an earlier report.…”

A close look at dose: Toward L-edge XAS spectral uniformity, dose quantification and prediction of metal ion photoreduction

“…4b reveals partly photoreduced K 3 [Fe(CN) 6 ], as it is known that the intensity ratio of the two peaks around 706 eV and 710 eV should be approximately 1:1 for the fully unreduced K 3 [Fe(CN) 6 ] (see also our measurement at DEIMOS in Fig. 3b) and that it will drop to almost 0:1 after full reduction [33]. Overall, all four spectra indicate varying, but majority signal from Fe 3+ entities.…”

“…On top of the absence of reported doses and the occurrence of different metal L-edge XAS spectra, for what are claimed to be identical compounds, we follow George et al [33] to point out that many modern 3rd generation synchrotron experiments are being carried out with steadily increasing photon flux and decreasing beam spot sizes, thereby significantly increasing flux densities. High energyresolution soft RIXS experiments require, for example, fluxes up to 10 13 ph/s and spot sizes in the range of 0.1 × 0.1 mm 2 .…”

“…Fig. 3a shows four spectra published by different groups [31][32][33][34]. Compared to KMnO 4 , the K 3 [Fe(CN) 6 ] spectral differences are relatively small.…”

“…Detailed early work by Collison and Young [66][67][68][69] exists on molecular compounds studied at their V, Fe or Ni L-edges, after which a period of silence on the topic followed. Recently, however, awareness of this issue has increased, as is illustrated by Mn and Fe L-edge studies, mainly on single molecule magnets, in which radiation-induced chemistry is explicitly acknowledged to occur [33,[70][71][72][73][74][75][76]. The common observation in all these references is the photoreduction of the metal ion site (other beam effects such as photo-oxidation, bond breaking and mass loss are outside the scope of this study).…”