180° pulse 

https://doi.org/10.1351/goldbook.08310
Pulsed radiofrequency signal in NMR that rotates the bulk magnetization vector (M0) of a nuclear spin to its opposing direction, effectively inverting the signal, (e.g., from the +z to −z axis).
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 681 [Terms] [Paper]
Citation: '180° pulse' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08310 RIS BibTex EndNote
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