Structural relaxation and vibrational density of states of amorphous tantala

We will exploit the unique capabilities of the NRAIXS spectrometer with high energy resolution (0.1 meV) at ID14 to probe the density of vibrational states (DOS) of a thin film of pure Ta2O5. We expect the DOS to show a significant temperature dependence at frequencies below 300 GHz (~ 1.2 meV), based on numerical simulations [1]. A proper description of the temperature and frequency dependence of the DOS above the Debye level will allow us to disentangle the harmonic and an-harmonic contributions. Our goal is to connect the high (GHz) and low (kHz) frequency regimes with the aim of elucidating the frequency dependence of the secondary relaxation processes in amorphous thin films.