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Chemistry type NMR: This is where I started. NMR as an analytical tool! I was an applications chemist at JEOL Analytical Instruments. I met a lot of very good NMR people during that time.
Coming soon!! Hg199 NMR and Coupling Constants
This is abstracted from a newsgroup discussion (sci.techniques.mag-resonance):
{thanks to all mentioned below for this information, and keeping the memory of front panel switches alive!}
Greg Brown wrote:
Why in MR spectroscopy are species of higher resonant frequency plotted to the left of lower frequencies? I have asked at several MRI MRS meetings and have yet to get an explanation for this interesting convention.
Carl Gregory wrote:
The convention goes back to the days when the experiment was done in "CW" mode using a fixed frequency crystal oscillator as the RF source. The magnetic field was swept from low to high, and the response plotted in real time on a strip chart from left to right. If you think about it, this means that at constant field, lower frequencies would be at the right end. This, of course, is still common in EPR.
Several large databases of spectra (Varian, Sadtler, etc.) were established at this time, and after the transition to pulsed NMR and FT data processing, the display was "reversed" to maintain compatibility with the existing data books.
Actually, some early heteronuclear (non-proton) spectroscopy WAS published with the frequency increasing to the right, which can be very confusing if you are looking at older literature.
Juergen Schulte wrote:
This convention still comes from the beginnings of NMR, when it was easier to change the field at constant frequency, than to keep the field constant and sweep the frequencies. This means that the field strength increases from left to right and led to the expressions "low field" (left) and "high field" (right). When it became more common to keep the magnetic field stable and record the frequencies, this convention stayed. At one point it was tried to invert the chemical shift scale to "tau = 10 - delta", but not very successful. In some older publications you may find proton chemical shifts expressed in tau.
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Well.. the BI-ANNUAL "Last Asilomar ENC" is coming up again!!
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