Phonon damping in thin films of Fe

The phonon density of states (DOS) in thin films of polycrystalline alpha-F e was measured by inelastic nuclear resonant scattering of synchrotron radi ation. The thin-film DOS exhibits significant deviations from the DOS of bu lk Fe, which we attribute to phonon lifetime broadening in the confined geo metry. The measured DOS can be described with a damped harmonic oscillator model for the phonons with different quality factors Q=25(2) and Q=13(1) fo r layer thicknesses of 28 and 13 nm, respectively. (C) 1999 American Instit ute of Physics. [S0021-8979(99)08413-3].