Probing magnetic order and disorder in the one-dimensional molecular spin chains CuF2(pyz) and [Ln(hfac)(3)(boaDTDA)](n) (Ln = Sm, La) using implanted muons

We present the results of muon-spin relaxation (mu+SR) measurements on antiferromagnetic and ferromagnetic spin chains. In antiferromagnetic CuF2(pyz) we identify a transition to long range magnetic order taking place at T-N = 0.6(1) K, allowing us to estimate a ratio with the intrachain exchange of T-N/vertical bar J vertical bar approximate to 0.1 and the ratio of interchain to intrachain exchange coupling as vertical bar J'/J vertical bar approximate to 0.05. The ferromagnetic chain [Sm(hfac)(3)(boaDTDA)](n) undergoes an ordering transition at T-c = 2.8(1) K, seen via a broad freezing of dynamic fluctuations on the muon (microsecond) timescale and implying T-c/vertical bar J vertical bar approximate to 0.6. The ordered radical moment continues to fluctuate on this timescale down to 0.3 K, while the Sm moments remain disordered. In contrast, the radical spins in [La(hfac)(3)(boaDTDA)](n) remain magnetically disordered down to T = 0.1 K suggesting T-c/vertical bar J vertical bar < 0.17.