Fast particle interactions with surfaces

M. S. GRAVIELLE

Buenos Aires

Simposio; Frontiers in Physical Sciences; 2016

International Center for Advanced Studies (ICAS)

The fast interaction of particles - atoms and molecules - and photons - ultrashort laser pulses - with surfaces is nowadays opening the way for the developing of powerful surface analysis techniques. Within the field of particle- solid interactions, one of the most streaking findings of the last decade corresponds to the observation of diffraction patterns produced by grazing impact of fast atoms on crystal surfaces. The most remarkable feature of these experiments, apart from the short wavelength, is that they produce surface images with unprecedented accuracy, allowing one to extract information on structural parameters smaller than the amplitude of thermal fluctuation of solid atoms. Our contribution was focused on the development of a semi-quantum method that provides a successful description of experimental diffraction patterns, including a clear representation of the main physical mechanisms. The model has been recently used to investigate the influence of the degree of coherence of the incoming wave packet in terms of the collimating conditions and the importance of van der Waals forces, among other issues.On the other hand, concerning fast photon-surface interactions, in the last time the technological achievement of lasers with pulse durations of the order of attoseconds is making it possible to study the behavior of electrons in condensed matter at their natural temporal orders. Such a remarkable experimental progress needs, however, to be accompanied by intensive theoretical research since the underlying quantum processes involve complex many-body mechanisms, whose complete understanding is still far from being achieved. Our recent work aims to contribute to the study of photoelectron emission from metal surfaces due to the interaction of ultra-short laser pulses. In particular, we investigate the influence of the crystallographic orientation of the surface on photoelectron spectra by analyzing surface-band structure and the induced potential effects.