Isotope Mass Abundance Spin Mag Moment
133Cs 132.905429 100% 7/2 +2.579
Cs I Ground State 1s22s22p63s23p63d104s24p64d105s25p66s 2S1/2 Ionization energy 31406.46769 cm-1 (3.893905 eV) Ref. WS87 Cs II Ground State 1s22s22p63s23p63d104s24p64d105s25p6 1S0 Ionization energy 186777.4 cm-1 (23.15744 eV) Ref. S81