AVS 50th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP7
Modeling Nano-Structure Evolution in the Continuum Step Model: Decay of Pb Crystallites@footnote1@

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: M. Degawa, University of Maryland
Authors: M. Degawa, University of Maryland
D.B. Dougherty, University of Maryland
K. Th@um u@rmer, University of Maryland
J.E. Reutt-Robey, University of Maryland
E.D. Williams, University of Maryland
T.J. Stasevich, University of Maryland
T.L. Einstein, University of Maryland
Correspondent: Click to Email
The evolution of crystalline nanostructures can be described accurately down to surprisingly small size scales using the continuum step model.@footnote 1@ Quantitative predictions for rates in general cases requires understanding the balance of competing kinetic mechanisms (step-edge attachment vs. terrace diffusion), competing driving forces (Gibbs-Thomson vs. step-step repulsions) and the influence of the initial shape and boundary conditions on the nanocrystal. Using numerical modeling, we demonstrate the evaluation of best fits in this multi-parameter space for the case of the relaxation of Pb crystallites after thermal quench@footnote 2@ and after triggered decay.@footnote 3@ The experimental system involves a volume-conserving change in the shape of the Pb crystal, which proceeds via cylindrically symmetrical layer-by-layer removal from the top facet of the crystal and transfer of mass to the sides of the crystal. The rate of peeling of all the layers yields non-unique combinations of the diffusion coefficient and attachment detachment rate, which can be limited by the range of physically reasonable the step-step repulsions. The time difference between sequential layer peelings, and the slow-down to the final state is governed by the choice of the boundary conditions and the step-step repulsions. The relationship of the best fit parameters to atomistic models for Pb, and the physical significance of the boundary conditions will be discussed. @FootnoteText@This work has been supported by the DOE-NNI and NSF-MRSEC.@footnote 1@A. Ichimiya, K. Hayashi, E.D. Williams, T.L. Einstein, M. Uwaha and K. Watanabe, Phys. Rev. Lett. 84, 3662 (2000). @footnote 2@K. Thurmer, J.E. Reutt-Robey, E.D. Williams, M. Uwaha, A. Emundts and H.P. Bonzel, Phys. Rev. Lett. 87, 186102-1 (2001). @footnote 3@D. B. Dougherty, K. Thurmer, M. Degawa, W.G. Cullen, J.E. Reutt-Robey and E.D. Williams, submitted for publication (2003).