Transcription of Chapter 13: Spectroscopy - Vanderbilt University
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11 Chapter 13: SpectroscopyMethods of structure determination Nuclear Magnetic Resonances (NMR) Spectroscopy (Sections ) Infrared (IR) Spectroscopy (Sections ) Ultraviolet-visible (UV-Vis) Spectroscopy (Section ) mass (MS) spectrometry (not really Spectroscopy )(Section )Molecular Spectroscopy : the interaction of electromagnetic radiation (light) with matter (organic compounds). Thisinteraction gives specific structural information. : mass spectrometry : molecular weight of the sample formulaThe mass spectrometer gives the mass to charge ratio (m/z), therefore the sample (analyte) must be an spectrometry is a gas phase technique- the sample mustbe vaporized. Electron-impact ionizationSample Inlet10-7 - 10-8 torrR-Helectron beam 70 eV (6700 KJ/mol)e_R-H+massanalyzerm/zionization chamber(M+) u23 mass mcharge z==B2 r22VB= magnetic field strengthr = radius of the analyzer tubeV= voltage (accelerator plate)The mass SpectrometerIonizationchamberIons of selectedmass/charge ratioare detectedIons of non-selectedmass/charge ratioare not detectedMagnetic Field, Bo4 Exact Masses of Common Natural IsotopesIsotope mass natural
The mass spectrometer gives the mass to charge ratio (m/z), therefore the sample (analyte) must be an ion. Mass spectrometry is a gas phase technique- the sample must be “vaporized.” Electron-impact ionization Sample Inlet 10-7 - 10-8 torr R-H electron beam 70 eV (6700 KJ/mol) e_ R-H + mass analyzer m/z ionization chamber (M+) proton 1 ...
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