  We theoretically investigate the effect of inhomogeneous light beams with
(twisted light) and without (plane-wave light) orbital angular momentum on
semiconductor-based nanostructures, when the symmetry axes of the beam and the
nanostructure are displaced parallel to each other. Exact analytical results
are obtained by expanding the off-centered light field in terms of the
appropriate light modes centered around the nanostructure. We demonstrate how
electronic transitions involving the transfer of different amounts of orbital
angular momentum are switched on and off as a function of the separation
between the axes of the beam and the system. In particular, we show that even
off-centered plane-wave beams induce transitions such that the angular momenta
of the initial and final states are different.
