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Topic: 2D NMR  (Read 2690 times)

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Offline dipesh747

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2D NMR
« on: January 12, 2012, 06:11:21 PM »
Hello, I have a few questions so please bare with me.

Dept experiment

So what I understand about this is that 2 pulse sequences are run in parallel, one directed at the protons and one directed at the carbons. With regard to the H proton sequence, is the 90-tau-180-tau to create a spin echo effect and then is the final theta y pulse used to refocus the magnetisation in the z axis (so it isn't detected in the coil). I think that it right but I'm not totally sure.

The carbon pulse sequence I am more confused with, in my notes I have written down this "proton spin state polarisation is converted into carbon transverse magnetisation via hetronuclear double and zero quantum coherence - "forbidden" spin transitions that do not correspond to any observable magnetisation.

So Proton spin state polarisation I assume is the alpha spins being excited through single quantum transitions. From my diagram it appears that this transfer (proton spin to transverse) occurs at the first 90 degree pulse for carbon. I don't understand what this means though, can anyone help me (I have not studied quantum mechanics and I can only find books with these types of explanations)

Here is a copy of the pulse sequence if needed http://www.google.co.uk/imgres?q=DEPT+experiment+pulse+sequence&um=1&hl=en&sa=N&biw=1366&bih=643&tbm=isch&tbnid=_YLfWg5HHgkzlM:&imgrefurl=http://www.chem.queensu.ca/facilities/nmr/nmr/webcourse/dept.htm&docid=pdYfO11YZZSDIM&imgurl=http://www.chem.queensu.ca/facilities/nmr/nmr/webcourse/images/dept/dept.gif&w=526&h=208&ei=W2gPT-DGBoiE8gPh2ajGAw&zoom=1&iact=hc&vpx=335&vpy=177&dur=7397&hovh=141&hovw=357&tx=149&ty=84&sig=100568421104679539420&page=1&tbnh=72&tbnw=183&start=0&ndsp=18&ved=1t:429,r:1,s:0

Thank you for any help in advance

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