Slide 5 of 11
Notes:
Note: Pulses excites the nuclei in a coherent way: they behave synchronously. After excitation they start precessing from the same point, all have the same frequency/ and move and behave identically. Thus, our excess magnetization will stay in sync and add up to a large signal. This is (commonly) called coherence. A special type of coherence are single quantum coherences ( in which only one type of nucleus is excited), if they are in the observable plane. We are able to detect those (and only those) with our receiver coil, and can commonly call them (observable) magnetization.
Try out: a) derive a product operator table for 90 degree pulses.
b) an example for precession: as in the vector presentation the two terms present the projections to the axes.
c) example for coupling= the cos- component is the projection to the starting axis, it does not precess. The other component consist of two vectors of opposite phase all the time.
d) go through precession of IxSy = four results= IxSycosIcosS + IxSxcosIsinS -IySysinIcosS-IySxsinIcosI
