Book by Timothy Claridge "High-Resolution NMR Techniques in Organic Chemistry" recommends calibrating homonuclear decoupling pulse power using Bloch-Siegert shift. It's somewhere in the "calibrations" section of the book.

Is there a particular reason that it would be inaccurate to set decoupler directly on resonance and calibrate width of 90 degree pulse by finding 360 pulse zero crossing?

Thanks.

Book by Timothy Claridge "High-Resolution NMR Techniques in Organic Chemistry" recommends calibrating homonuclear decoupling pulse power using Bloch-Siegert shift. It's somewhere in the "calibrations" section of the book.

Is there a particular reason that it would be inaccurate to set decoupler directly on resonance and calibrate width of low power 90 degree pulse by finding 360 pulse zero crossing?

Thanks.