NMR Background Nuclei of isotopes which possess an odd number of protons, an odd number of neutrons, or both, exhibit mechanical spin phenomena which are associated with angular momentum. This angular momentum is characterized by a nuclear spin quantum number, I such that I =1 n, where n is an integer 0, 1, 2, 3. Those nuclei for which i=0 do not possess spin angular momentum and do not exhibit magnetic resonance phenomena. The nuclei of C and 0 fall into this category. Nuclei for which I =/ include H, "F, C, ap and N, while H and"N ave Since atomic nuclei are associated with charge, a spinning nucleus generates a small electric current and has a finite magnetic field associated with it. The magnetic dipole, of the nucleus varies with each element. When a spinning nucleus is ed in a magnetic field, the nuclear magnet experiences a torque which s to align it with the external field. For a nucleus with a spin of /, there are two allowed orientations of the nucleus parallel to the field (low energy) and against the field(high energy). Since the parallel orientation is lower in energy, this state is slightly more populated than the anti-parallel, high energy state.(Figure 1) ① If the oriented nuclei are now irradiated with electromagnetic radiation of the proper frequency, the lower energy state will absorb a quantum of energy and spin-flip to the high energy state. When this spin transition occurs, the nuclei are said to be in resonance with the applied radiation, hence the name nuclear magnetic resonance. The amount of electromagnetic radiation necessary for resonance depends on bothNMR Background Nuclei of isotopes which possess an odd number of protons, an odd number of neutrons, or both, exhibit mechanical spin phenomena which are associated with angular momentum. This angular momentum is characterized by a nuclear spin quantum number, I such that, I = 1/2n, where n is an integer 0,1,2,3...etc. Those nuclei for which I = 0 do not possess spin angular momentum and do not exhibit magnetic resonance phenomena. The nuclei of 1 2C and 1 6O fall into this category. Nuclei for which I = 1/2 include 1H, 1 9F, 1 3C, 31P and 1 5N, while 2H and 1 4N have I = 1. Since atomic nuclei are associated with charge, a spinning nucleus generates a small electric current and has a finite magnetic field associated with it. The magnetic dipole, ? of the nucleus varies with each element. When a spinning nucleus is placed in a magnetic field, the nuclear magnet experiences a torque which tends to align it with the external field. For a nucleus with a spin of 1/2, there are two allowed orientations of the nucleus; parallel to the field (low energy) and against the field (high energy). Since the parallel orientation is lower in energy, this state is slightly more populated than the anti-parallel, high energy state. (Figure 1) If the oriented nuclei are now irradiated with electromagnetic radiation of the proper frequency, the lower energy state will absorb a quantum of energy and spin-flip to the high energy state. When this spin transition occurs, the nuclei are said to be in resonance with the applied radiation, hence the name nuclear magnetic resonance. The amount of electromagnetic radiation necessary for resonance depends on both