Isotope Mass Abundance Spin Mag Moment
227Ac 227.027750 Trace 3/2 -1.1 228Ac 228.031015 Trace 3
Ac I Ground State 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p66d7s2 2D3/2 Ionization energy 41700 cm-1 (5.17 eV) Ref. S74 Ac II Ground State 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p67s2 1S0 Ionization energy 94800 cm-1 (11.75 eV) Ref. MHRS74