Question

a. What happens to nuclei with nonzero magnetic moments when they are placed in a strong external magnetic field?

b. In a typical NMR experiment, a small amount of the compound to be analyzed is dissolved in a deuterated solvent. Explain what a deuterated solvent is and why it is used for NMR analyses.

Answer 1

a.) When the nuclei of nonzero magnetic moment is kept in an external magnetic field, it will align either along or opposite to field applied. The ones aligned against the field () state is lower in energy and that along the field () is higher in energy. The lower enery state is populated more.

b.) In deuterated solvent the hydrogen isotope proton present is replaced by another isotope of hydrogen deuterium which has a zero nuclear magnetic moment. Its done as proton has non-zero nuclear magnetic moment, so if the solvents used for the NMR has protons it will also interact with the field and give their corresponding data, which will interact with the sample data and cause error in the experiment. Thus if deuteriate it since its nuclear magnetic moment is zero there won't be any interaction and the data won't have any error.