University of Birmingham > Talks@bham > Physics and Astronomy Colloquia > Atomic dynamics in nano-time, as well as on the nano-scale

Atomic dynamics in nano-time, as well as on the nano-scale

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Studying the dynamics of atoms and molecules on surfaces has always proven a challenging field, since it requires both high spatial and temporal resolution. In particular, simultaneous measurement on both ‘atomic’ length and time scales (nanometre length scales and picosecond to nanosecond timescales, respectively) is not possible with most techniques [1]. However, despite the fact that this ‘atomic’ regime corresponds to many of the physical properties and processes that underly fundamentally and technologically important behavior, the experimental limitations mean it remains largely unexplored.

We have recently developed a unique helium-3 spin-echo apparatus [2], that provides a novel approach, enabling simultaneous measurements on both these scales. Consequently, we have recently been able to access a wide range of new physics. In fact, the spin-echo technique can be applied in many ways, enabling ultra-precise measurements of surface structure and vibrations, as well as diffusion and adsorbate-substrate nanoscale friction.

We give an overview of the scope of the technique and focus on its application to transport, diffusion and friction, which we illustrate through a range of recent measurements. We show how the fundamental transport of isolated species can be measured, and how subsequent adsorbate substrate potentials can be developed [2,3,4]. We then illustrate the sensitivity of the technique to correlated motion, which provides an accurate probe of adsorbate-adsorbate interactions. Finally, we show how the complex interplay between adsorbate-substrate and adsorbate-adsorbate interactions can give rise to a range of behavior [4,5] and how an accurate dynamical measurement is crucial to achieving a realistic model of physical systems.

References: 1) J. V. Barth, Surf. Sci. Rep. 40, 75 (2000). 2) A. P. Jardine et. al. Science 304, 1790 (2004). 3) G. Alexandrowicz et. al., Phys. Rev. Lett. 93, 156103 (2004). 4) G. Alexandrowicz et. al., Phys. Rev. Lett. 97, 156103 (2006). 5) A. P. Jardine et. al., J. Phys: Condens. Matter (in press).

This talk is part of the Physics and Astronomy Colloquia series.

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