CHMB42H3 Lecture Notes - Absorption Band, Shortwave Radio, Bond Length
Document Summary
Small amount of compound is introduced into spectrometer and is vaporized and ionized: electron ionization-mass spectrometry (ei-ms) is most common method for ionization. Produces a molecular ion, a radical cation a species with an unpaired electron and positive charge. So much kinetic energy in molecular ions, often fragment into smaller cations, radicals, neutral molecules, and other radical cations. Positively charged fragments are accelerated and deflected in a curved path in analyzer tube according to the mass-to-charge ratio (m/z) of the fragment: particles with same m/z can be separated from others. Mass spectrum a graph of the relative abundance of each fragment plotted against its m/z value: charge (z) on all fragments reaching collector relatively the same (+1), therefore m/z is the molecular mass of the fragment. A mass spectrum only records positively charged fragments. Neutral molecules, neutral fragment s and negative ions are pumped out.
