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++.

No abstract

The foll&ng evidence has been obtained for t h e existence of americium in the formal valence of plus sixr (1) ammonium peroxydisulfate in 0e2M n i t r i c or perchloric acids t o a no$luoride-precipitable e t a t e e ( 2 g f l l .fp a the characteristic pi& of Am(II1) changes t o a s t r o n g yellaw color. ( 2 ) "he absorption spectrum of suoh an oxidized solution was measured w i t h a Beckilram model DU speotrophotomter using q u a r t z micro c e l l s and Om1 -s e n s i t i v i t y scale. attended by a growth of h ( V ) absorption b u t no increase in the Am(II1) absorpticm. Ameriefum(I1I) ie completely oxidized byThe decrease w i t h time of these new absorption peaks isThe rate of decrease of the 991 peak is meh greater i n the absence of s u l f a t e , and the u l t r a B i o l e t absorption i s altered.& .the addition of sodium acetate, a yellow compound of t e t r a h e d r a l s t r u c t u r e was obtsiaed which was isomorphous w i t h Pthe analogous NaM *Acornpounds (Ba i s U or Pu). The r e f r a c t i n index of sodium americyl a c e t a t e has the expected value of 10528 (compamd with 1.501 and 1.518 fer the uranium and plutonium coqounds, respectively). There were no b ( I I 1 ) o r Am(B) absorption l i n e s in t h i s ompound{ The compound WBS dried w i t h acetom, t r e a t e d w i t h excess ferrous amonium s u l f a t e and back-titrated with c e r i c sul@$ate.f The amount of americum was determined by radio-assay. A value of 2.9 was obtained f o r the number of equivalents on reducing Am(@ t o Am(II1).

According to the literature4•6 the highest oxide of sodium that can be obtained by combustion of the metal in an excess of oxygen is the peroxide, Na2C>2. The superoxides of potassium, rubidium and cesium may be prepared by the same method.6•6 Although previous investigators7 have studied the reaction between alkaline earth metal lower oxides with oxygen at elevated temperatures and pressures in attempts to prepare higher oxides, no similar experiments have been performed with sodium peroxide. Holt and Sims5 passed oxygen at atmospheric pressure over sodium peroxide at 300-350°for sixteen hours but obtained no evidence of oxygen absorption. In a previous report8 from this Laboratory, dealing with the rapid oxidation of sodium in liquid ammonia, evidence for the existence of sodium superoxide was described.9 In the present investigation sodium peroxide has been subjected to treatment with oxygen at high pressures and temperatures in order to explore the possibility of preparing higher oxides by this method. Such treatment results in the formation of high yields of sodium superoxide. The preparation and magnetic properties of this substance are discussed in this paper.

The foll&ng evidence has been obtained for t h e existence of americium in the formal valence of plus sixr (1) ammonium peroxydisulfate in 0e2M n i t r i c or perchloric acids t o a no$luoride-pre-2 N-X 4 1/9/51 jed /-'f &*/ DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government.