Electron Paramagnetic Resonance Investigations of Divalent Americium and Trivalent Curium in Strontium Chloride

The cubic-site electron-paramagnetic-resonance spectra of divalent americium and trivalent curium (

5 f^{7}

configuration) in Sr

{Cl}_{2}

have been observed. The ground states are

Γ_{6}

doublets, indicating that the fourth-order parameters

c

of the cubic crystal-field Hamiltonian are negative. Because of the relatively small cubic crystal-field interaction with the

{}^{8}S_{\frac{7}{2}}

state, the

Γ_{6}

ground-state transitions were anisotropic, permitting a determination of the zero-field splitting. Additionally, an excited state (

Γ_{7}

) resonance was detected for curium, and curium resonances were observed at temperatures as high as 200 K. The

g_{J}

value obtained for

{Cm}^{3 +}

was 1.9264±0.0008 while the

{Am}^{2 +}

g_{J}

value was 1.9283±0.0008. Assuming that the sixth-order parameters are negligible, the values of

c

are -1.83±0.02

{cm}^{- 1}

for curium and -1.92±0.16

{cm}^{- 1}

for americium. The hyperfine structure constants for americium were determined to be 83.9±0.1 G for

{}^{241}{Am} (I = \frac{5}{2})

and 8.32±0.1 G for

{}^{243}{Am} (I = \frac{5}{2})

. The previously unknown nuclear spin of

{}^{245}{Cm}

was determined to be

\frac{7}{2}

with an

A

value of 19.0±0.2 G. By comparison with

{}^{241}{Am}

and

{}^{243}{Am}

, an estimate of the magnetic moment

| μ ({}^{245}{Cm}) | = (0.5 \pm 0.1) μ_{N}

was made.

This publication has 21 references indexed in Scilit: