Iosif Sogolov
Sun. 3 Jan.10,
20:49
[Reply (7 of 12) to:
'90 excitation pulse vs 180 inversion pulse'
started by: 'Bjorn Redfors'
on Sat. 27 Jun.09]
 Category:
Basics and Physics
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| 90 excitation pulse vs 180 inversion pulse |
prior 90: spins precess around B0 uncoherently, there for the sum of their projections on TRANSVERSE plane is ZERO, they are "unfocused" in this plane. 90 and right after: all above mentioned spins are forced to rotate around B1, it should be stressed - in only one for ALL of them chosen direction of rotation (depends of B1 direction) to the TRANSVERSE plane, they all will come compact to this plane and now they do give here NET MAGNETIZATION, become "focused".
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