/到 生物核磁共振波谱学 NMR in Biological Science 2 Basics of nmr THNMR AN
生物核磁共振波谱学 NMR in Biological Science 2. Basics of NMR THNMR YAN
What is nmr? NMR, Nuclear Magnetic Resonance, is a phenomenon which occurs when the nuclei of certain atoms are immersed in a static magnetic field and exposed to a second oscillating magnetic field 核磁共振是指核磁矩不为零的核,在外磁场的作用下,核 自旋能级发生塞曼分裂( Zeeman splitting),共振吸收某 特定频率的射频( radio frequency,RF)辐射的物理过程。 Ref:http://www.nmr.de THNMR AN
What is NMR? NMR, Nuclear Magnetic Resonance, is a phenomenon which occurs when the nuclei of certain atoms are immersed in a static magnetic field and exposed to a second oscillating magnetic field. 核磁共振 是指核磁矩不为零的核，在外磁场的作用下，核 自旋能级发生塞曼分裂(Zeeman splitting），共振吸收某一 特定频率的射频（radio frequency, RF）辐射的物理过程。 Ref: http://www.nmr.de THNMR YAN
2.1 Spin Physics What is spin? Spin is a fundamental property of nature like electrical charge or mass Spin comes in multiples of 1/2 and can be t or- Protons, electrons, and neutrons possess spin. Individual unpaired electrons, protons, and neutrons each possesses a spin of 1/2 THNMR AN
2.1 Spin Physics What is spin? Spin is a fundamental property of nature like electrical charge or mass. Spin comes in multiples of 1/2 and can be + or -. Protons, electrons, and neutrons possess spin. Individual unpaired electrons, protons, and neutrons each possesses a spin of 1/2. THNMR YAN
2.1 Spin Physics Nuclei with spin 1)/=0,当中子数、质子数均为偶数;如:12C、16O 2)/=半整数,当中子数与质子数一为奇数,一为偶数 如:/=1/2:1H、13C、15N、19F、31P /=3/2:23Na、35Cl、3K. /=5/2:17O、25Mg 3)/=整数,当中子数与质子数均为奇数,如2H、14N
2.1 Spin Physics Nuclei with spin 1）I = 0，当中子数、质子数均为偶数；如：12C、 16O… 2）I = 半整数，当中子数与质子数一为奇数，一为偶数 如： I = 1/2：1H、 13C、 15N、 19F、 31P… I = 3/2：23Na、 35Cl、 39K… I = 5/2：17O、 25Mg… 3） I = 整数，当中子数与质子数均为奇数，如2H、 14N…
原子核的自旋角动量与磁矩 自旋量子数不为零时,原子核具有自旋角动量P P=v(+少 1=√/(+1)h 2兀 原子核磁矩与自旋角动量之间存在如下关系: μ=yP Y为磁旋比 magnetogyric ratio)或 旋磁比 gyromagnetic ratio)
原子核的自旋角动量与磁矩 自旋量子数I不为零时，原子核具有自旋角动量P 原子核磁矩与自旋角动量之间存在如下关系： 为磁旋比(magnetogyric ratio)或 旋磁比(gyromagnetic ratio) ( 1) 2 ( 1) = + = + I I h P I I = P
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
磁矩的空间量子化 量子力学原则:外磁场中,自旋角动量与磁矩的取向是量 子化的 自旋角动量在z轴上的投影由磁量子数m决定,m有2H+1个 可能取值,即-,-/+1,,/-1, P=mh 核磁矩在z轴上的投影 u,=yP=ymh 磁矩和磁场的相互作用能 E=-μ·B0=-2B 原子核相邻能级间发生跃迁所需要的能量 THNMR AN △E=AmB0=hB
磁矩的空间量子化 量子力学原则：外磁场中，自旋角动量与磁矩的取向是量 子化的 自旋角动量在z轴上的投影由磁量子数m决定，m有2I+1个 可能取值，即 - I, -I + 1, … , I -1，I 核磁矩在z轴上的投影 磁矩和磁场的相互作用能 原子核相邻能级间发生跃迁所需要的能量 P z = m z = P z = m E B0 = −z B0 = −• E mB0 B0 = = THNMR YAN
Properties of Spin When placed in a magnetic field of strength Bo, a particle with a net spin can absorb a photon, of frequency v. The frequency V depends on the gyromagnetic ratio, y of the particle h=△E=YhB0 Memo: Vo=(/2 )x Bo y B THM For hydrogen, v=42. 5 8 MHZ/T AN
Properties of Spin When placed in a magnetic field of strength B0 , a particle with a net spin can absorb a photon, of frequency . The frequency depends on the gyromagnetic ratio, of the particle. 0 = (/2) B0 For hydrogen, = 42.58 MHz / T. 0 B0 Memo: = THNMR YAN hv E B0 = =
Nuclei with Spin Nuclei Unpaired Unpaired Net Spin Protons Neutrons (MHz/T) HHP 0 1/2 42.58 6.54 31 2 №NF 111111 1/2 17.25 3/2 1.27 3.08 10.71 1/2 40.08 THNMR YAN
Nuclei with Spin Nuclei Unpaired Protons Unpaired Neutrons Net Spin (MHz/T) 1 H 1 0 1/2 42.58 2 H 1 1 1 6.54 31P 0 1 1/2 17.25 23Na 2 1 3/2 11.27 14N 1 1 1 3.08 13C 0 1 1/2 10.71 19F 0 1 1/2 40.08 THNMR YAN
The larmor frequency can be understood as the recession frequency of the spins about the axis of the magnetic field B THNMR YAN
The Larmor frequency can be understood as the precession frequency of the spins about the axis of the magnetic field B0 THNMR YAN