CLARK METHOD OF RECORDING LINESHAPES

The absorption or dispersion spectrum of a nuclear spin system can be obtained by an analog integration of the phase-detected free-induction decay (FID), while sweeping the magnetic field (Clark method). Simple rules are given to optimize the signal-to-noise ratio. The possibility of applying the Clark method to the study of broad spectra is investigated. When the perturbation Hamiltonian hYCO is larger than the rf Hamiltonian, the effects of the former during the pulse cannot be neglected. However, to first order in H0, the expression for the integrated FID takes a particularly simple form which has an immediate physical interpretation. The Clark method is extended to the analysis of inhomogeneous and solid echoes. When the conditions of an ideal experiment are not met, the Clark method gives a recording which may be described as a distorted lineshape. However, the distortions can sometimes be suppressed or reduced and are easily related to their cause. © 1979.