A theoretical study of the biselective double pulsed field gradient spin-echo NMR experiment

Abstract

The application of a biselective radiofrequency pulse to a coupled homonuclear spin system produces effects that are exploited in liquid-state NMR experiments. The insertion of such an RF pulse in a double pulsed field gradient spin echo sequence results in a module for the biselective production of antiphase magnetization states. Biselectivity is obtained through cosine modulation of a singly selective pulse profile. A full description of the module behaviour is possible by means of four parameters, of which two are related to a property called ‘pulse ellipticity’. The theory is in good agreement with the experimental results and numerical simulations. It is thus possible to predict how a maximum of antiphase magnetization can be produced.

Keywords:

• Liquid-state NMR
• Selective pulses
• Static field gradients
• Spin echo

Acknowledgement

I thank Dr. K. Plé for linguistic advice.