Mark Bradley

Prof. Bradley

Professors Mark Bradley and Patrick Shipman (CSU Math) have received word that their joint research on ion-induced pattern formation will be supported by a three-year, $280,000 grant from the National Science Foundation.

When an energetic ion strikes a solid surface, one or more atoms can be ejected from the solid. Bombarding a flat solid surface with a broad ion beam therefore results in erosion of the solid. Naively, one would expect that the solid surface would simply remain flat as it is eroded. Instead, a remarkable variety of self-assembled nanoscale patterns can form, including mounds arranged in hexagonal arrays of astonishing regularity. In 2010, Mark and Patrick advanced a theory that explains the genesis of these arrays. A sequence of snapshots from a simulation of their model shows the development of a highly ordered array of mounds (see the picture below). To date, Mark has been invited to speak on this work at thirteen international conferences held in India, Germany, the U.S. and elsewhere. Mark and Patrick will explore methods to produce new and exotic types of order and to enhance the degree of order in their newly funded research.


A sequence of snapshots from a simulation of Bradley and Shipman’s model for the formation of highly ordered arrays of nanoscale mounds. The initial state was a nearly flat, rough surface. Each snapshot was taken looking down at the surface. High points are white and low points are black, and time increases from left to right

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