Introduction to Geochemistry

Fusion of Elements Heavier than Ni
! Neutron capture, principally
! s-process: neutron flux in 2nd generation stars or red giants is low
enough that nuclides can undergo # decay between capture events
• Can yield nuclides up to Bi
Example step 1: 62 Ni + 1 n
63 Ni + $
step 2: 63 Ni 63 Cu + # - + "
! r-process: high neutron flux can allow sequential capture of many
neutrons before decay can occur
• Occurs in final minutes of a red giant, during supernova detonation
! p-process: low-probability reactions where multiple protons are
captured (by bombardment) simultaneously
• Characteristic of supernova detonations
• Yields particular isotopes such as 74 Se, 92 Mo