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Unformatted text preview: MSE 2020 2/10/2011 Page 1 of 5 Presentat ion: M ass Spectromet ry • J.J. Thompson – father of mass spectrometry o Deflected deionized neon/electrons with magnetic/electric fields • Measures the mass/charge ratio • Amount of deflection is measured o Depends on the mass of the particle • Sample prep o Doesn’t have to be a pure sample but must be in the gaseous state (vaporization may be a step) and ionizable o Ionization Sample made into a gas Positively ionize the sample by knocking off electrons with high energy beam (fragmentation of sample/molecules occurs) o Acceleration Give all molecules the same kinetic energy Sample is pushed through a chamber with 3 slits (each with a different potential so as to accelerate the charge ions) All ions from the sample are made into a beam/stream o Reflection Field (magnetic or electric) is applied Lighter ions are deflected more than heavier ones Positive ions are deflected in the opposite direction as negative ions o Detection Ions collide with a metal plate MSE 2020 2/10/2011 Page 2 of 5 Collision energy is transferred into electrons, emitted ions/photons This energy transfer creates a signal that is picked up by the detector • Data Analysis o Can’t assume that the charge is +1 If it’s not +1, there will be a matching line at half the mass/charge (if...
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- Spring '09