  The purpose of this paper is to prove the uniqueness theorem of solutions of
eigenvalue equations on one end of Riemannian manifolds for drift Laplacians,
including the standard Laplacian as a special case; we shall impose "a sort of
radiation condition" at infinity on solutions. We shall also provide several
Riemannian manifolds whose Laplacians satisfy the absence of embedded
eigenvalues and besides the absolutely continuity, although growth orders of
their metrics on ends are very complicated.
