Isotope Mass Abundance Spin Mag Moment
162Er 161.928775 0.14% 0 164Er 163.929198 1.61% 0 166Er 165.930290 33.6% 0 167Er 166.932046 22.95% 7/2 -0.5665 168Er 167.932368 26.8% 0 170Er 169.935461 14.9% 0
Er I Ground State 1s22s22p63s23p63d104s24p64d105s25p64f126s2 3H6 Ionization energy 49262 cm-1 (6.1077 eV) Ref. WSPC78 Er II Ground State 1s22s22p63s23p63d104s24p64d105s25p64f12(3H6)6s (6,1/2)13/2 Ionization energy 96200 cm-1 (11.93 eV) Ref. SR65