Infrared spectra were measured at 80 K for dimethyl ether (CH3OCH3, DME) and dimethyl ether-d(6) (CD3OCD3, DME-d(6)) with increasing amounts of exposures to metal substrates, Ag(110), Cu(110), and their atomic oxygen-reconstructed surfaces, p(2 x 1)O-Ag(110) and p(2 x 1)O-Cu(110). At relatively lower surface coverages, the IR spectra of DME on Ag(110) and Cu(110) in the 1500-800 cm(-1) region give rise to IR bands mainly ascribable to A(1) species, including symmetric COC stretching (v(s)(COC)) bands at 903 cm(-1) on Ag(110) and 895 cm(-1) on Cu(110), while at nearly saturation coverages, the adsorbate gives IR bands ascribable to B-1 and/or B-2 species in addition to the A(1) bands with the v(s)(COC) band discretely sifted to 915 cm(-1) on Ag(110) and to 901 cm(-1) on Cu(110). Similar distinct spectral changes were observed also for DME and DME-d(6) on the reconstructed surfaces. The stepwise spectral changes were interpreted in terms of a conversion from a state of DME with the C-2 axis almost perpendicular to the surfaces to a state with the C-2 axis tilted away from the perpendicular orientation. Fermi resonance effects cause stepwise but complicated spectral changes in the CH3 stretchin g vibration region of DME during the conversion. The changes strongly depend on the kind of the substrates, in contrast to the spectral changes in the 1500-800 cm(-1) region, suggesting that the analyses of Fermi resonances can delineate subtle differences in the DME/substrate interaction modes among the substrates. Density functional theory (DFT) molecular, orbital calculations were carried out on the cluster models of DME/Cu(110), where the oxygen atom of DME is coordinated to two copper atoms in the surface of metal clusters consisting of 12 copper atoms in the first layer and six copper atoms in the second layer. The results of calculations reproduce the observed frequencies appreciably well, substantiating the coordination interaction model.