Evolution of dynamical motions in monolayer protected metal-clusters

Here we report orientational dynamics in monolayer protected metal-cluster (MPC) systems as studied by quasielastic neutron scattering (QENS) technique. Experiments carried out using two different instruments having very different energy windows, thus covering a time scale of 10-9-10-12 s. Clear evidence of absence of 'rotator phase' has been found in isolated MPCs (Au-SC18H37, Au-SC8H17 and Au-SC6H13), a superlattice MPC (Ag-SC18H37) as well as planar thiolates (Ag-SC6H13, Ag-SC12H25, Ag-SC18H37) at room temperature. However, dynamics were found to evolve on increase of temperature and its behaviour is found to be different in the superlattice and isolated cluster systems. Detailed dynamical informations for MPCs are obtained for the first time in these systems. © 2003 Elsevier Science B.V. All rights reserved.