{{Infobox model parameter| name = {{PAGENAME}}| param = <onlyinclude>''Φ<sub>ex</sub>''<noinclude/onlyinclude>| desc = Fast exchange factor.| equation = {{:pA}}{{:pB}}{{:deltaomega2}}| units = rad<sup>2</sup>.s<sup>-2</sup>}}
The fast exchange factor, in rad2.s-2. This is equal to:{{:Phiex}} = pApBΔω2</noinclude> [[Category:Relaxation dispersionanalysis]]