Nuclear Magnetic Resonance Spectra of Some Hydrocarbons

The study of the nuclear magnetic resonance spectrum of protons in ethyl alcohol made by J. T. Arnold has been extended to other liquid compounds which are more amenable to an exact calculation of their energy levels and transition probabilities under the influence of a small radio-frequency perturbation. Resulting recordings of these spectra are shown to be in agreement with the spectra predicted by a simple Hamiltonian proposed by Hahn and Maxwell as well as by Gutowsky, McCall, and Slichter. New evidence has been found which indicates that lines in a given spectrum have different widths.A method has been demonstrated whereby a definite spin coupling may be associated with a definite group of nuclei. This is achieved by simultaneously applying a large radio-frequency field with a frequency near to the resonance frequency of one group of nuclei and a small radio-frequency field to produce transitions within another group. In this case any structure due to the spin coupling between the two groups is greatly modified.A new and simple procedure has been demonstrated whereby the magnitude of the radio-frequency field at the sample may be accurately determined with the aid of a small auxiliary radio-frequency field.