Low-Temperature Optical Absorption of Americium Halides

Abstract

Absorption spectra at low temperatures are reported for AmCl₃, AmBr₃, and AmI₃. Bathochromic shifts have been generally observed in the series from the chloride to the iodide. These shifts are comparable to those observed in lanthanide halides. Hypersensitive transitions have been observed in AmI₃. A number of new assignments of excited levels of Am(III) are proposed on the basis of intensity calculations. Electrostatic, spin–orbit, and configuration‐interaction parameters were obtained by direct diagonalization and least‐squares fitting to 29 observed levels for AmCl₃. The parameter values in cm⁻¹ are: $E^1\text{\hspace{0.17em}=\hspace{0.17em}3582.8}$ , $E^2\text{\hspace{0.17em}=\hspace{0.17em}17.276}$ , $E^3\text{\hspace{0.17em}=\hspace{0.17em}334.30}$ , ${\xi }_{\text{5f}}\text{\hspace{0.17em}=\hspace{0.17em}2593.3}$ , $\text{α\hspace{0.17em}=\hspace{0.17em}21.634}$ , $\text{β\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}158.48}$ , $\text{γ\hspace{0.17em}=\hspace{0.17em}1240.4}$ .