Raman spectra of magnesium chloride thin films

We have observed lattice vibrations of MgCl2 thin films for the first time by surface enhanced Raman scattering induced by a silver underlayer. Two Raman active bands of the MgCl2 crystal, Eg and A1g, were observed at ∼160 and 240 cm−1. The band width of A1g mode was about 20 cm−1. The Raman spectra indicate that the lattice structure of the evaporated MgCl2 film is well ordered like that of a polycrystal. We have also measured Raman intensity of A1g mode, varying the film thickness from 0.6 to 7 nm. This film thickness dependence indicates that the Raman enhancement occurs within a very short distance from the substrate.