A Perkin-Elmer Optima 3000 axially viewed ICP spectrometer was used to study the effects of EIEs on the spatially dependent ion and atom emission intensities from Mg containing solutions and slurries. Using the Mg 279.553 nm ion and 285.213 nm atom line emission profiles, ion:atom emission intensity ratios were measured, with and without EIEs, across the plasma to visualize the changes in energy transfer processes when an EIE is present. Transport effects are negated when this ion:atom/ion:atom ratio is employed. In the presence of an EIE, both atom line ratios and ion line ratios are enhanced for solutions and slurries and this enhancement increases in the order Li < Na ⩽ K < Cs. Profiles of ion_EIE:ion and atom_EIE:atom ratios show greater enhancement for the excited ion population that the excited atom population. This indicates an increased departure from simple ‘Saha’ LTE conditions for both solutions and slurries with EIEs. While similar energy transfer processes are seen for solutions and slurries, under these matrix conditions, the magnitude of the enhancement in slurries is less than that of solutions when Li and Na are present. A reduced atomization efficiency for slurries relative to the matrix-matched solutions is implied. This relative atomization efficiency is seen to change for different systems. A refractory MgO slurry, which contained particles up to 4 µm in diameter, gave a relative atomization efficiency of 80–85% in the absence of an EIE. In the presence of an EIE, the relative efficiency increased up to 100% in the order Li < Na ≈ K ≈ Cs. This effect may be attributed to (i) a ‘real’ increase in atomization efficiency, (ii) subtle changes in the rejection of a larger solid particle fraction or (iii) a combination of both. Atom line ratio profiles show spatially dependent structure, similar to a ‘caldera’, when EIEs are present. The rim of this atom caldera is the interface between the central analyte channel and the plasma body. These profiles allow the energy transfer processes that occur in this region to be visualized. The presence of EIEs causes this region to be enhanced and increase in the order, Li < Na ⩽ K < Cs. Ion line profiles are relatively flatter. Ion:atom ratio profiles show that an energy transfer process involving ion population enhancement occurs at the centre of the analyte channel when an EIE is present.