Trick known as the spin-echo
most favorite angle for maximum signal - magnetization lies on the transverse plane
We have to apply the oscillating magnetic field for just a right amount of time. That time is known as 90 degree pulse.
We've turn the magnetization vector through 180 degrees
This idea of refocusing is a bit like time reversal process
We have to start with the 90 degree pulse, we wait for the magnetization decay away, and then we apply the 180 degree pulse
multiple echo experiment
amplitude is die away [zanika] in time
irreversible process - proces nieodwracalny
fundamental limitation - podstawowe ograniczenie
Stosunek amplitudy FID (sygnału początkowego) do amlitudy sygnału echa wskazuje na wielkość stałej zaniku sygnału (the rate of decay)