The Dynamic Pair Distribution Function allows one to get information of the local dynamics of a crystalline material in the real space and can be interpreted as the probability of two atoms in a lattice being both a certain distance and oscillating at a certain frequency. Here we perform a comparative study of face-centered cubic nickel of two different inelastic neutron scattering measurements located at Oak Ridge National Laboratory in Tennessee, USA, and the ISIS Neutron and Muon Source in Oxfordshire, United Kingdom, which demonstrate that equivalent splitting of nearest neighbor distances and changes in bond length is achieved. A splitting is seen at 2.48 Å when the phonon at ~23 meV is activated and 4.36 Å when the phonon at ~16 meV is activated in both sets of data which correspond to the out-of-phase motions of face centers in the nickel crystal lattice relative to the origin. These two data sets were compared after optimization of data with respect to the individual instrumental setups. Optimization was realized through careful comparison of background treatments, effects of collimators, sample holder effects, and most importantly the role of incident energy. These results demonstrate the success of the method in a simple system which can be expanded to the study of more complicated solid-state systems such as molecular solids and has the potential to be an alternative to traditional local probe methods such as infrared and Raman spectroscopy. This study heightens the similarities and differences of the unique instrumental setups.

Comparative study of dynamic pair distribution function analysis on inelastic neutron spectrometers in the US and the UK through the analysis of nickel

ACS Spring 2022

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