5 ms·

Maybe I’m slow here, but the authors said they couldn’t get a molecular ion in mass spec, but the ESR shows an electron in the center like would be expected for

• devilbunny 4y ago
  Mass spec depends on the ion surviving the passage through an electron beam. They can't get a molecular ion because it blows apart in the process - they just get the fragments. Normally, you get the big fragments and at least some of the whole molecule ions. Not here. Too unstable. ESR is more gentle.
  • s0rce 4y ago
    Not all mass spec use an electron beam (in fact I think most do not), one of the most common for analyzing organic molecules uses electro-spray ionization (ESI) and it is relatively gently but I assume you are generally correct in that they couldn't get the whole molecule to fly, it either didn't ionize or fragmented.
    • devilbunny 4y ago
      Thank you. It's been a good while since I studied how mass spec actually works. And the ones we used were not new at the time (they were from a local company that donated their older machines to my university). Maybe I only remember how ours worked. The organic chem students didn't get to use the nice computerized FFT NMR machine that was in the basement - that was for analytical chem students and research projects. No, the NMR's you got to use in organic just scanned each frequency and had a plotter that traced your result on paper. I did think that the single peak on both fluorine and carbon NMR was pretty cool.