Institutt for fysikk og teknologi

William Allison (Univ. of Cambridge)

Fellesseminar: Did it jump, or was it pushed? How to disentangle aspects of molecular motion at surfaces


William Allison

The dynamics of molecular motion at surfaces is important in surface phenomena such as growth and reactivity. For an experimentalist, there is a formidable challenge in understanding the processes at an atomic scale, since distances are fractions of a nanometre and times are typically picoseconds. Among other things, barriers to motion must be identified together with the role of adsorbate-substrate interactions as well as inter-molecular interactions. In addition the rates of energy transfer between the adsorbate and the substrate are crucial in determining the absolute rates of a given process [1]. I will describe a series of careful experiments that highlight many of these issues, using a range of atomic and molecular adsorbates on single crystal metallic substrates [2,3]. What emerges is a greatly expanded understanding of the underlying dynamics and a better appreciation of the strengths and limitations of existing theoretical models.