  For spherically symmetric repulsive Hamiltonians we prove the Besov bound,
the radiation condition bounds and the limiting absorption principle. The
Sommerfeld uniqueness result also follows as a corollary of these. In
particular, the Hamiltonians considered in this paper cover the case of
inverted harmonic oscillator. In the proofs of our theorems, we mainly use a
commutator argument invented recently by Ito and Skibsted. This argument is
simple and elementary, and dose not employ energy cut-offs or the microlocal
analysis.
