First determination of the spin relaxation properties of a nitronyl nitroxide in solution by electron spin echoes at X-band: A comparison with Tempone

► We compared spin relaxation in solution between Tempone and a nitronyl nitroxide. ► We measured T1 and T2 of the radicals by electron spin echo in the range 195-310 K. ► Our analysis exploits experimental T1 and T2 to separate the relaxation terms. ► For similar radical sizes the nitronyl nitroxide has consistently longer T1 and T2. ► The larger anisotropic dipolar interaction causes faster relaxation in nitroxides.