The absorption spectra of neptunium ions in perchloric acid solution

Theoretical study of the electronic spectra of neutral and cationic NpO and NpO2

“…[16][17][18][19][20][23][24][25][30][31][32][33][34][35] Due to the environment influencing considerably the spectral intensities in solutions and solids, our Einstein coefficients computed for the isolated molecules may not be suited for comparison. In contrast, the transition energies suffer less from the environment.…”

“…14 and 15. Both ions were investigated by UV/VIS absorption spectroscopy in aqueous acidic solutions, [16][17][18] accompanied by separate studies on NpO 2 +19 and on NpO 2…”

Precipitation of neptunium dioxide from aqueous solution

“…Figure 3-15 is a sample spectrum of the oxidized neptunium and shows the characteristic Np(V) absorption peaks at 617 and 980 nm. 43 Evidence of Np(VI) would be apparent by an absorption peak at 1223 nm. 43 The ionic Np(V) was then precipitated as NpO 2 OH(am) by addition of 0.1 M NaOH until a green suspension formed in solution.…”

“…43 Evidence of Np(VI) would be apparent by an absorption peak at 1223 nm. 43 The ionic Np(V) was then precipitated as NpO 2 OH(am) by addition of 0.1 M NaOH until a green suspension formed in solution. 21,44 The green precipitate was collected by centrifugation in a 5 mL pyrex centrifuge tube.…”

Neptunium_Oxide_Precipitation_Kinetics_AJohnsen

“…A purified stock solution of NpO2 + chloride media was prepared by precipitation of NpO2OH(am) via NaOH addition, the precipitate rinsed three times with DI water, and the remaining solid dissolved in a minimum of 0.1 M HCl [18,19]. The resultant neptunium concentration was determined via low-energy photon spectrometry (LEPS) using the 29.374-keV gamma-ray and the oxidation state was confirmed as NpO2 + with UV/Vis spectrophotometry (Guided Wave Model 260) [20]. 96-17, respectively) to determine the overall ionic strength of the solution and to detect any gross pH electrode solution leakage over time.…”