β-delayed proton decay of89Ru

89Ru was synthesized in the reaction of58Ni (36Ar, 2p3n) on the basis of a “p-y” coincidence measurement by using a He-jet tape transport system, and its β-delayed proton emission with a half-life of (1.1 ± 0.2) s was investigated. The β-delayed proton spectrum of89Ru populating the lowlying states in88Mo was obtained, and the final state proton branching ratios to the low-lying 2+ and 4+ states in88Mo were estimated to be 100:6. Based on the statistical model calculations, the ground state spin of89Ru was preliminarily assigned to be 5/2+ or 7/2±, and the mass excess of89Ru was deduced to be -59.5 MeV.