Infrared Spectroscopy of Metal-MgO Single Crystalline Composite Films

Abstract
Infrared transmission spectra were measured for single crystalline composite films of nm-sized metal (Au, Fe and Cr) crystallites and magnesium oxide (MgO). The absorption lines of the TO phonon of MgO were observed around 400 cm-1. The widths of absorption lines in Fe-MgO and Cr-MgO composite films are about three times wider than those of vacuum-deposited MgO films, whereas they are twice as wide in the Au-MgO composite films. These features are tentatively understood in terms of the difference in the bonding strength of the metals and oxide.