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BEGIN:VEVENT
DTSTAMP:20260917T020552Z
LAST-MODIFIED:20140128T172433Z
DTSTART:20140207T170000Z
DTEND:20140207T180000Z
UID:event1195@bu.edu
URL:http://physics.bu.edu/internal/events/show/1195
SUMMARY:Irradiation-Induced Morphology Evolution
DESCRIPTION:Featuring Scott Norris\, Southern Methodist University\nHosted 
	by: Karl Ludwig\n\nPart of the Biophysics/Condensed Matter Seminar Series.\
	n\nAbstract:\n\nIon beam irradiation is an essential basic tool in many ind
	ustries\, used widely for chemical doping and surface processing.  For over
	 50 years\, spontaneously-forming ripple-like structures have been occasion
	ally observed during this process\, but the observation in 1999 of highly-o
	rdered\, hexagonal arrays of nanoscale dots on irradiated GaSb has sparked 
	an intense renewed interest in ion-induced surface modification.  It has be
	en hoped that this process could form the basis of a "bottom-up" process to
	 cheaply and rapidly manufacture arrays of nanostructures\, or induce surfa
	ce coatings with tunable opto-electronic pproperties.  However\, despite ma
	ny years of accumulated study of ion irradiation\, and thorough knowledge o
	f the generic ingredients for ordered structures\, a definitive explanation
	 for their origin in this system has remained elusive.\n\nIn this talk we w
	ill describe several lines of mathematical inquiry into this problem:  (a) 
	the use of molecular dynamics simulations of individual ion impacts to info
	rm a multi-scale continuum theory\, (b) a continuum mechanical description 
	of the effect of beam-induced stress on the dynamics of the irradiated film
	\, and (c) investigations on the effects of chemistry via a model of phase 
	separation.  Although a robust mathematical model of the basic physics\, th
	at accurately predicts experimental results across a range of parameter val
	ues\, appears to remain just beyond reach\, each of these lines of inquiry 
	has improved our fundamental understanding of this fascinating system withi
	n certain parameter regimes\, and several patterns simpler than hexagonal d
	ots now appear explainable with reasonable experimental agreement.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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