Absorption Spectra of Red Uranium(III)Chloro Complexes in Strong Hydrochloric Acid.

Heterogeneous photocatalytic removal of U(VI) in the presence of formic acid: U(III) formation

“…4 was surely overlapped by the broad U(IV) band. Remarkably, an important increase in the absorbance in the 350-600 nm range was observed (see inset), together with a change of color in the suspension, from transparent to deep orange, which coincides with the reported absorbance of U(III) species [19,20,26,27], corresponding probably to a U(III)-HCOOH complex [28][29][30]. Other peaks corresponding to U(III) were not observed, surely due to a masking by the strong U(IV) signals [19,20].…”

Review of Electronic Absorption Spectra of Molten Salts

“…Laport·e-allowed Rydberg transitions of the 5r-> 5r-l 6d type are well known (68,70,73) and have oscillator strengths ranging from about 10-1 for U(III) to about 1<)~2 for Am(III).…”

Rationalization of Spectra of Rare Earths in Condensed Matter

“…Thus, the one-electron energy difference between the five 5d-or 6d-like orbitals provide moderately broad bands [5,21,26,27,[31][32][33][34][35] presumably having a mechanism rather similar to the change of the number α of antibonding electrons in the Tanabe-Sugano diagram [10,14,43,44]. It should not be accepted (without first pondering a moment) that the bandwidth of absorption (and of any luminescence) is due exclusively to "breathing" multiplying all the ground state M-Χ distances (in a given instant) by the same factor close to 1.…”

“…Obviously, inter-shell transitions in Ln(ΙΙ) and Ln(ΙII) 4f q → 4 f q -1 5d [25][26][27] and in U(III) [21] and M(IV) 5fq → Φ5fq-1 6d transitions [51] involve mixtures of characteristics of "internal" transitions in partly filIed 4f and 3d, 4d or 5d shells. Thus, the one-electron energy difference between the five 5d-or 6d-like orbitals provide moderately broad bands [5,21,26,27,[31][32][33][34][35] presumably having a mechanism rather similar to the change of the number α of antibonding electrons in the Tanabe-Sugano diagram [10,14,43,44].…”

“…It is worth noting that frequent minerals and rocks, which would be white in their iron-free "idealized" formula (as Na, Mg, Al, K, Ca silicates) usually are grey to almost black due to simultaneous presence of iron(II) and iron(III) known from greenish black Fe(OΗ)2+x" and prussian blue KFe(CN) 6 FuII As first observed in coloured, luminescent fluorites Ca1-xLnxF2 by Przibram [20], lanthanides(II) such as dark green Sm(ΙΙ), pale yellow Eu(II) and Yb(II) show strong absorption bands. In analogy to the conditions for Laporte-allowed transitions in atomic spectra, it is agreed today that the excited state belongs to 4 f 4-1 5d, much like strong absorption bands in the visible of grey uranium(III) acquoions, their raspberry-red chloride complexes [21] and U(III) in crystals show the excited configuration 5 f 2 6d. This type of inter-shell transition is less common in the 3d group, although iron(II) acquoions have excited 3d54s states [3], copper(!)…”