I have another question about MRI physics. I was going to make a new thread, but it seemed easier to just post it here since you all seem to know a lot about the topic.
When the perpendicular RF pulse is applied in a MRI machine the net magnetic moment tilts from the Z axis into the X-Y plane. What happens to the individual magnetic moments of all the protons though? Do the individual magnetic moments tip as well?
My previous understanding was that the individual magnetic moments dont change orientation, instead the tipping of the net magnetic moment is caused by the precession of all the protons in phase (which creates the X-Y component) and the elevation of some protons from the low energy state to the high energy state (thus shrinking the net Z component). Is this true?