  The factorization method of Infeld and Hull is applied to the radial
Schr\"{o}dinger equation for $d$-dimensional isotropic harmonic oscillator and
various ladder operators are defined. The radial energy eigenstates are
expressed in terms of the generalized Laguerre polynomials and their properties
are shown to follow from the expressions involving the ladder operators. In the
same way as the harmonic oscillator we also obtain the bound energy eigenstates
of the Morse oscillator.
