原子核在外磁场中的运动 P(z P(2 1 P Spin-122 in a magnetic field both i and l, are quantized the nuclear spin can only be orientated in( I+ 1) possible ways, with quantum number m ranging from-I to I(-1,-1+1,-1+2,.D) the most important nuclei in biology are the spin-1/2 isotopes H, 3C, 5N °F,and3P as spin-1/2 nuclei they can assume two states in a magnetic field, a(m 1/2)andβ(m=+1/2) THNMR YAN原子核在外磁场中的运动 - in a magnetic field, both I and Iz are quantized - the nuclear spin can only be orientated in (2 I + 1) possible ways, with quantum number m ranging from -I to I (-I, -I+1, -I+2, … I) - the most important nuclei in biology are the spin-1/2 isotopes 1H, 13C, 15N, 19F , and31P - as spin-1/2 nuclei they can assume two states in a magnetic field, a (m = - 1/2) and b (m = + 1/2) THNMR YAN