Electronic transitions of the manganate(V) ion in aqueous solution: a resonance Raman study

Abstract

The resonance Raman spectra of manganate(V) ion in aqueous solution in the visible and near-UV regions were studied. The maximum in the Raman excitation profile (REP) of the totally symmetric vibrational mode (n 1 ) at ca 600 nm is assigned to a charge-transfer transition with appreciable d-d character. Owing to marked orbital mixing in such systems, the observed Raman enhancement could also be assigned to a d-d transition with a high charge-transfer character. The absence of overtones in the Raman spectrum indicates a small shift in the equilibrium Mn-O bond distances (d r ) between the excited and fundamental electronic states. This finding was confirmed by the calculation of the REP within the time formalism approach. The best fitted d r value is lower than the corresponding reported values for manganate(VII) and manganate(VI) ions. Two models were used in the calculations, in which whether a single or two electronic transitions were considered in the visible range of the absorption spectrum. Similar d r values were obtained with both models.

Spectroscopic Investigation on BaSO4:(Mn6+, Mn5+) Crystal

“…The PL bands peaking at ∼1183 nm is attributed to the 1 E → 3 A 2 transition of Mn 5+ ion. 27,39,40 It is well-know that undoped BaSO 4 crystal has no NIR luminescence. Thus, NIR luminescence of Mn ion doped BaSO 4 crystal results from Mn ion.…”

X-ray and vibrational spectroscopy of manganese complexes relevant to the oxygen-evolving complex of photosynthesis

“…Even though a great many Mn compounds, relevant to the OEC, have been published, only a few of these of compounds have been studied by XANES 35,[186][187][188][189][190][191][192][193][194][195][196] or Mn Kβ XES. 46,[197][198][199] In fact, some of the compounds involved are manganese salts, such as Mn II Cl 2 , or oxides, such as Mn 2 O 3 , which are less relevant to the OEC. 38,190,193,194,198 The focus of these studies is on either the influence of an oxidation-state change 191,192,196,197 or a structural change [186][187][188]195 …”