Using nitronyl nitroxide radicals it is possible to prepare purely organic ferromagnets without inclusion of any transition metal or lanthanide ions. Muons are uniquely sensitive to the magnetic properties of these materials; they are highly suitable for study at ISIS because the internal fields are typically low. Two isomers have been identified as showing dramatically different magnetic properties (one is two-dimensional, the other consists of an array of dimers) which we believe occurs because of the different packing of the radicals. The aim of the experiment is (i) to determine whether the 2D arrangement of radicals shows magnetic order and (ii) to investigate the intriguing possibility that for the other system, the muon could attach via a muonium state, thereby splitting the dimer. These possibilities will be investigated experimentally, comparing results with DFT+mu calculations.