PHYS1008 Study Guide - Final Guide: University Of Manchester, Sine Wave, Angular Momentum
2 Aug 2018
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Document Summary
Process by which the transverse components of magnetisation (mxy) decay/dephase. T2 = the time required for the transverse magnetization to fall to approximately 37% (1/e) of its original value. T= t2 in the equation and it works out to be 37% Removing the energy which caused the m to be shifted away from b0 causes dephasing, and they protons comprising m are no longer aligned in the mxy. T2 is the time constant for dephasing of transverse magnetisation (mxy) May occur with or without energy transfer. Anything causing t1 relaxation also causes t2 relaxation, but t2 relaxation can occur without t1 relaxation. T2 = loss of phase coherence from the xy-plane. Spin system = slightly unequal distribution of angular momentum in z-direction = net magnetisation (m) 90 degree pulse rotates entire system converting initial asymmetry of z-components into asymmetry of transverse (xy) components resulting in a temporary statistical (cid:862)phase (cid:272)ohere(cid:374)(cid:272)e(cid:863)
