CHEM 6AL Lecture Notes - Lecture 10: Diamagnetism
Document Summary
Odd # will give nucleus a spin. Need an odd # of protons or neutrons in the nucleus. Even # has no spin & therefore can"t be studied by nmr. Beta spin state (cid:523)higher energy(cid:524) line against the magnetic field. Alpha spin state (cid:523)lower energy(cid:524) line up with magnetic field. More energy is needed to align the magnetic moments against the field. Nuclei in the alpha spin state promoted to the beta spin state. Difference in energy between the alpha & beta spin states increases as the strength of the applied magnetic field increases. Strength of magnetic field is proportional to the operating frequency of the spectrometer. All the hydrogens do not experience the same magnetic field. Caused by circulating electrons inducing a local magnetic field opposite of the applied magnetic field. Delta(e) between alpha, beta spin states is dependent on bo, as well as the local electronic environment. Local electrons shield the nucleus from the applied magnetic field (bo)
