The reaction between MgF2 and tris (8-hydroxy-quinoline)aluminum (Alq 3)has b een studied using high-resolution electron-energy-loss spectroscopy (HREELS).The reaction between MgF2 and Alq3 occurs in the cases of MgF 2 deposited on A lq3 and Alq3 on MgF2.The shift of the loss peak corresponding to the out-o f-plane ring bend is observed to be similar to that for Mg deposited on Alq 3.T he HREELS spectra indicate that Mg is produced from MgF2 deposited on Alq3,a nd interacts with Al,O and N in Alq3.Analysis of the HREELS results s uggests that Mg is not in the Alq3 molecule plane.