a) Name at least three methods of ion activation.
- Collision-induced dissociation (CID)
- Surface-induced dissociation (SID)
- Infrared multiphoton dissociation (IRMPD)
- Electron capture dissociation (ECD)
- Electron transfer dissociation (ETD)
b) Tell the differences between ion-neutral collision in the high-energy and in the low-energy regime.
In magnetic sector and TOF instruments, He is typically used as the collision gas because the energy transferred during (a single) high-energy collision (keV) is comparatively large; in addition He reduces the risk of charge exchange due to its high IE. In the low collision energy regime of quadrupole and ion trapping instruments (1-200 eV) Ar and Xe are frequently employed to make CID more effective due to multiple collision with those heavier atoms.
c) In IRMPD, how many photons from a continuous wave carbon dioxide laser of 10.6 µm wavelength do you need to increase the internal energy of an ion by about 3 eV?
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