We present a detailed study of the scattering properties of ultracold
mixtures of bosonic potassium atoms. We locate 20 previously unobserved
Feshbach resonances in isotopic 39K-41K mixtures. These are assigned to s-wave
molecular channels by comparison to an asymptotic bound state model and coupled
channels calculations. Additional Feshbach resonances are studied in spin
mixtures of a single potassium isotope, both in 39K and 41K. In particular, we
characterize the parameters of a selected 39K Feshbach resonance by
radio-frequency association of Feshbach molecules. Our results could be
exploited to refine the model potentials for potassium scattering. Furthermore,
these new Feshbach resonances enlarge the range of experiments possible with
degenerate Bose-Bose mixtures.Comment: 9 pages, 3 figures, 1 tabl
