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I ran a typical dosy expt and got an unexpected increase on echo intensity in the begining of the array. The first 3 points have increasing intensity, then it goes down more or less as guaussian.

Did anybody here ever see that? It would make sense if i start with a present gradient on the opposite direction, but i didnt.

pulse sequence=stebpgp1s, bruker bipol. grad. with spoil grad. Gradients are arrayed from 2% to 60%. Liquid sample on DMSO, Molec. Weight ca. 6000, T=25C.


asked May 31 '12 at 11:36

fid's gravatar image


2 Answers:
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I have seen this once as a result of spinning the sample during acquisition. The decay curve showed an unexpected increase in signal intensity for the first 2-3 experiments. The rest of the curve followed a "more or less" Gaussian decay, but the curve was not smooth and the fitting algorithm discarded almost all of the points. After turning off sample rotation, the DOSY was run again and a normal decay curve was obtained.


answered Jun 04 '12 at 09:34

sagebowser's gravatar image


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I have the same problem, but sample spinning is not turned on. Was spinning the solution to your problem, or was something else causing the initial increase?


answered Jun 03 '13 at 09:14

mikaelastewart's gravatar image


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