  Changes in the magnetic moment of an electron near a dielectric or conducting
surface due to boundary-dependent radiative corrections are investigated. The
electromagnetic field is quantized by normal mode expansion for a
non-dispersive dielectric and an undamped plasma, but the electron is described
by the Dirac equation without matter-field quantization. Perturbation theory in
the Dirac equation leads to a general formula for the magnetic moment shift in
terms of integrals over products of electromagnetic mode functions. In each of
the models investigated contour integration techniques over a complex wave
vector can be used to derive a general formula featuring just integrals over
transverse electric and transverse magnetic reflection coefficients of the
surface. Analysis of the magnetic moment shift for several classes of materials
yields markedly different results from the previously considered simplistic
'perfect reflector' model, due to the inclusion of physically important
features of the electromagnetic response of the surface such as evanescent
field modes and dispersion in the material. For a general dispersive dielectric
surface, the magnetic moment shift of a nearby electron can exceed the previous
prediction of the perfect-reflector model by several orders of magnitude.
