[Winga]

After the molecules being ionized by high energy e-, the molecular ions may also be fragmented. What  causes the fragmentation? (Due to the unstability of molecular ions or the high energy e- break the bonds?)

[nocommentes]

Of course "Due to the unstability of primary molecular ions" which decay to more stable fragments, which can than rearrange in more stable ions and radicals which then are detected. More stable ions have high strength in spectrum.