The mutation effect caused by low energy ion beam implantation into dry seeds has been accepted and turned into practical application. But its mechanism is still not clearly understood. According to the energetic ion range theory

ions with hundreds of keV energy can’ t directly affect the nuclei of the cell inside the embryo part of the seeds underneath the thick seed coat. It is obviously important to measure the concentration-depth distribution of the implanted ions in seeds for study of the mechanism. 200keV V + ions were implanted into dry seeds of peanut with a dose of 9×10 16 ions/cm 2

then the seeds were sliced up into 15μm thickness along the incident beam direction . The concentration of the V in each slice was measured with PIXE (Particle Induced X-ray Emission). It is shown that the concentrations of the V in un-implanted peanut are lower than the detection limit of PIXE. But the concentrations in the slices of implanted peanut up to 121—135μm depth are higher than the PIXE detection limit. More than 98% of V are in the first slice ( corresponding to 0—15μm depth)

however

the rest part of V distribute over a wide depth range. This fact indicates that the structure in peanut seeds is not homogeneous

the implanted ions can reach a much deeper depth than that predicted by the range theory.