Threshold voltages for hyperbolic secant inversion pulses.

G S Payne; M O Leach

doi:10.1002/nbm.1940050307

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Threshold voltages for hyperbolic secant inversion pulses.

G S Payne·M O Leach

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Abstract

Spin inversion produced by hyperbolic secant RF pulses is independent of pulse amplitude once a threshold value is exceeded. A semi-empirical formula for these pulses has been derived by application of analytical solutions to the Bloch equations. This predicts the required coil voltages for inversion as a function of inversion bandwidth and side-to-width parameter mu, based on knowledge of a reference voltage for the loaded coil. The voltage required is shown to increase linearly with bandwidth but to fall with the mu, approximately as (1/mu)0.4. Experimental confirmation is presented, and factors affecting choice of pulse parameters are discussed.

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G S Payne, M O Leach. Threshold voltages for hyperbolic secant inversion pulses.. https://doi.org/10.1002/nbm.1940050307

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