6.2.2 Charge Site Influences the Reaction Site

Where a particular molecule ionizes (insofar as ionization can be considered localized) determines in part where and how decomposition occurs. For example:

• Non-bonding nitrogen electrons in amines have small ionization energies; a small ionization energy implies that more of the incident electron collision energy is available to energize the molecule for decomposition. The mass spectra of amines often lack molecular ion signals.
• Amines commonly undergo the so-called $\alpha$ cleavage that produces characteristic ions. Ionization at a nitrogen site (in an amine) therefore results in a pattern in the mass spectrum.

Not all decomposition reactions occur at the charge site, but the charge site influences the site of reaction.