The Solution Absorption Spectra of Americium(III), (V), and (VI)

Abstract

Detailed absorption spectra of Am(III), (V), (VI), and Eu(III) in perchloric acid were obtained over the range 200–800 mμ using the Cary Recording Spectrophotometer. Molecular extinction coefficients obtained from the average of several determinations are given for each absorption peak of the americium species. No vibrational fine structure similar to that reported for U(VI), Np(V), Np(VI), and Pu(VI) was found in the visible and ultraviolet spectra of Am(V) and (VI). This fine structure has been interpreted as arising from symmetrical metal-oxygen vibration in ions of the type MO2+ and MO2++.

Radiolytic Oxidation of Am (III) to Am(V) in NaCl Solutions

“…2 based on a total Am concentration of 3.4 χ 10" 6 mole/L in the solution, which is determined by liquid scintillation counting, is consistent with Am (III) and Am(V) concentrations of 4.7 χ 10" 7 mole/L and 2.9 χ 10" 6 mole/L, respectively. The indicated Am(V) concentration amounts to 86% of the total Am in solution based on molar absorptivities e(503 3nm) = 390L/mole and e(513.6nm) = 41 L/mole, which are also characteristic of Am 3+ and AmO^ in acid solutions [8,9]. It is possible that the weak absorption indicated at 507.6 nm is due to a small amount of Am carbonate complex ions [6], which may have been produced by the sorption of C0 2 from the air during the sampling of the solution for spectroscopy.…”

“…3, clcarly illustrates characteristic absorption bands at 514,648 and 716 nm [8,9]. Their molar absorption coefficients are determined to be e = 41, e = 5 and e = 58, respectively.…”

“…Further investigations showed the oxidation of Am(OH) 3 to Am(0H) 4 in 0.2M NaOCl (pH > 7) at ~ 90°C [4], Subsequently, it was found that Am (III) could also be radiolytically oxidized to Am(V) in concentrated K 2 C0 3 solutions without benefit of an extra oxidizing agent [5]. However, this experiment was carried out with mixtures of Am (III) and Cm (III) at a very high dose rate of aradiation equal to 100-300W/L( (3)(4)(5)(6)(7)(8)x 10 3 Ci/L).…”

Americium dioxocations in solid: crystal structures and absorption spectra of the new complexes [Am V O2(dipy)OOCCH3(H2O)] and Cs2[(Am VI O2)2(SO4)3]

“…As a rule, the spectra of actinide-ions exhibits the prominent absorption bands of the Laporte-forbidden ff transitions, which are useful tool for the identification of actinides oxidation state. The solution spectra of hydrated ions AmO 2 + aqua and AmO 2 2+ aqua have long been known [25,26]. The presence of complexing anions in solution leads to a hypsochromic or bathochromic shifts of the main absorption bands (514 and 716 nm for Am(V); 663 and 996 nm for Am(VI)).…”

Americium

“…3 I 7 with their absorbance peaks at 513.7 nm (e $ 45 L mol cm À1 ) and 716.7 nm (e $ 60 L mol cm À1 ), respectively, are the main absorbance bands of the AmO þ 2 ion in aqueous solutions. Absorbance spectra of Am(V) have been recorded in H 2 SO 4 (Werner and Perlman, 1950), HCl (Hall and Herniman, 1954;Stadler and Kim, 1988;Runde and Kim, 1994), HClO 4 (Asprey et al, 1951;Stephanou et al, 1953), NaCl ( Stadler and Kim, 1988;Runde and Kim, 1994), and in 2 M Na 2 CO 3 (Bourges et al, 1983;Hobart et al, 1983b) (Fig. 8.15).…”