The electromagnetic (EM) waves associated with the polariton modes of
bulk dielectrics are quantized using a procedure that accounts for bot
h the Em and matter fields. The interaction of electrons with these po
lariton fields is described using the minimal coupling (e/m)A . p int
eraction Hamiltonian where A is the transverse vector potential operat
or of the polariton field, p the electronic momentum and m its effect
ive mass. The electron-polariton interaction in the bulk is demonstrat
ed to be closely linked to the behaviour of the polariton group and ph
ase velocities. The same quantization procedure is then employed to de
scribe the EM fields associated with the interface polaritons of a GaA
s/AlAs quantum well system. The coupling leads to a dependence of the
scattering rate on the group and phase velocities of the surface modes
, just as it does for the bulk excitations. In contrast to the case in
the bulk, it is shown that these modes are important for relaxing the
electron energy in narrow wells.