CHEM 311 Lecture Notes - Reflectron, Krahn People, Electric Field
Document Summary
Mass spectroscopy: a technique used to measure the mass-to-charge ratio of molecules and atoms. Often characteristic ions produced by an induced unimolecular dissociation of a molecule are measured. These characteristic ions can be used to finger print a molecule for identification or identity confirmation. Essential mass spectroscopy components: source of ions in vacuum or at atmosphere, mass analyzer must be under vacuum, ion detection device, data acquision system. Ion kinetic energy (ke) = qv = zev. Where; e = 1. 6 x 10-19 coulomb: fixed energy can be transferred to ion. 1 electron volt (ev) = 1. 6022 x 10-19 joules = 96. 5 kj/mol: ion beam accelerated has significant energy. Ke = m v2 = zev: different mass ions have different velocities. Magnetic fields exert a force on a moving electrical charge that is perpendicular to the direction of motion. Electric sector (e) ev ev + ev ev - . Advantages: high resolution possible (with electric, simultaneous monitor isotopes, versatile ionization techniques.
