AVS 62nd International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS+AS-WeA

Invited Paper SS+AS-WeA3
Strategic Applications of the Vibrational Dynamics of the Outer Layer of Metal Nanoparticles

Wednesday, October 21, 2015, 3:00 pm, Room 112

Session: Surface Dynamics, Non-Adiabaticity, and Single Molecule Phenomena
Presenter: Marisol Alcantara Ortigoza, University of Central Florida
Correspondent: Click to Email
The structure characterization, stability and thermal properties of nanoparticles (NPs) are topics of fundamental and technological significance. This information, however, is not always readily available from experiment. Moreover, the vibrational density of states VDOS of small (<2 nm) metal NPs definitely does not have a quadratic decay at the low-frequency end, for which the thermal properties cannot be obtained from the VDOS as Debye proposed in 1912. The features particular to the VDOS of NPs will be rationalized in terms of the charge density distribution around low-coordinated atoms, the quasi-radial geometric distribution of NPs, force constant variations, degree of symmetry of the nanoparticle, discreteness of the spectrum, and the confinement of the eigenmodes. I will present an explanation and application of the enhanced low- and high energy tails of the vibrational density of states (VDOS) of nanoparticles with respect to their bulk counterparts, as well as show that the eigenmodes defining the two extremes of the VDOS are not that alien to widely studied surface phonons. I will show that the high- and low-energy tails of the VDOS of NPs may be a powerful tool to reveal information about their chemical composition and geometric structure of small NPs. For example, the size of the confinement gap at the low-frequency end of the VDOS and the extent by which the high-frequency end surpasses the bulk limit may indicate whether a NP is bulk-like or non-bulk-like and the extent to which it is disordered or segregated. Regarding thermal properties, I will also show that for NPs with a largely discrete VDOS, the frequency of their fundamental mode may largely determine their thermal properties.