Practice question

Electron ionization is a classic hard ionization method where vaporized organic molecules enter a high-vacuum ion source and encounter a 70 eV electron beam. Energetic collision ejects an electron from the neutral molecule, generating a radical cation denoted M+• containing both an unpaired electron and positive charge. This energetically unstable molecular ion undergoes extensive fragmentation into characteristic daughter ions, providing rich structural fingerprints for library matching. Radical anions remain minor products, free electrons are removed by repeller, and neutrals escape detection, making radical cations the hallmark species for metabolite identification in gas chromatography-mass spectrometry.