unsur138Properties of the nuclide isotope Caesium-138. Parent Nuclides. Direct parent isotope is: 138 Xe. Nuclear Isomers. Nuclear isomers or excited states with the activation energy in keV related toProperties of the nuclide isotope Caesium-138. Parent Nuclides. Direct parent isotope is: 138 Xe. Nuclear Isomers. Nuclear isomers or excited states with the activation energy in keV related to