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It was 40 days ago when I mentioned the student license of TopSpin and other products, once pricey, that are now free for academic users. Knowing that many students prefer the MacBook and would like to run authentic Mac applications on it, I am going to write about the student promotion of iNMR . It is not free, but it is as cheap as it can possibly be. It's 39 euro (equivalent to 49 USD or 32 British pounds or 4200 Yens). What's so special about this license is that it is... perfectly normal! I mean: it INCLUDES direct customer support and this is quite valuable for a student that is learning NMR and a new software at the same time. Is this program difficult to learn? As for every NMR program, it CAN be hard if you are so familiar with TopSpin (or VNMR, or Jeol Delta) that you can't adapt yourself to anything else. The learning curve of iNMR is actually incredibly smooth if you start processing easy examples (1-D spectra or well acquired 2-D like TOCSY, HSQC...) before mo...

I want to show you a proton spectrum that has puzzled me during the last weeks. It contains something that's quite typical and something that I can't explain. I have processed the spectrum in two different ways, with zero-filling and without it. The spectrum without zero-filling is black, the spectrum with zero-filling is green (the number of points is doubled). This detail is the bottom part of the TMS signal (magnified to show the ringing effect). Where does the ringing come from? TMS is a small symmetric molecule and its protons have a long relaxation time. Their signal persists at the end of the FID. When we add the zeroes after the signal, a step is created. The FT of the step is the ringing that we see. The spectrum without zero-filling doesn't contain the step, so there is no ringing. The period of the ringing is exactly 1 point. In simpler words: odd points are positive, even points are negative. Things are not so simple, actually, because the rule is reversed on t...