17. Spectroscopy
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describe the steps that occur to produce a mass spectra
• sample vapourised and turned to gas • electron beam bombards gaseous molecules, knocking out an electron to form molecular ions • some of these molecular ions break apart into smaller fragment ions • the ions are deflected through a magnetic field which separates them according to their mass/charge ratio • separated ions are detected and their data is displayed as mass spectrum
what does a mass spectrum represent ?
represents abundance of each fragment against its m/z value, providing critical info about samples composition
what does the molecular ion peak represent ?
indicates relative abundance of M+ ions = molecular mass
why do smaller m+1 peaks appear ?
represents molecular ions that include carbon-13 isotope