MARKET 1 Lecture Notes - Lecture 26: Electronvolt, Ion Source, Isotopic Signature
Document Summary
A mass spectrum shows the mass of the molecule and the its pieces/fragments. Ms is an instrumental method in analytical chemistry that helps identify the type and amount of chemicals present in a sample according to the mass-to-charge ratio and abundance of gas-phase ions. A mass spectrum is a pattern of the ion signal generated in a mass spectrometer as a function of the mass-to-charge (m/z) ratio. The masses of the molecular ions and fragments are used to determine the elemental composition or isotopic signature of a compound. Depending on the information obtained the chemical structures of molecules can be determined. Molecules (in their gaseous phase) are introduced into the mass-spectrometer. Ionised molecules with high internal energies (3 5 ev) will fragment. Separation of these molecules/fragments according to their masses (better mass/charge ratio) Mass spectrum plots the mass/charge ratio vs relative intensity: z usually equals 1. High vacuum necessary to avoid interaction (collisions) between ionised molecules/fragments.
