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SUMMARY:Electrostatic Interaction between randomly charged objects - Dr Al
 i Naji (DAMTP)
DTSTART:20101001T110000Z
DTEND:20101001T120000Z
UID:TALK26398@talks.cam.ac.uk
CONTACT:Dr Mark Miller
DESCRIPTION:That likes repel and opposites attract is a statement that doe
 s not seem to hold only for electrostatics but has found its way from phys
 ics into broader aspects of life as well.  In the past several years it ha
 s\nbecome clear though\, that in the case of strongly charged bodies likes
  can attract as well. This constitutes a major shift in paradigm in the th
 eory of charged soft matter in general and has allowed us to get a deeper 
 understanding of complicated phenomena like DNA collapse.  We now show tha
 t there can be long-range\nattractive (or repulsive) forces even between n
 et-neutral dielectric objects if they carry small amounts of positive and 
 negative charges\, randomly frozen within their body or on their surface. 
 This long-range interaction arises from the interplay between randomness a
 nd image charge effects and stands at odds with the commonly accepted view
  that neutral objects interact only via multipolar or van der Waals (vdW) 
 forces. It is shown that a long-range disorder-induced attraction between 
 neutral bodies in vacuum may even swamp the ubiquitous Casimir-vdW force u
 nder certain circumstances. Indeed\, such an additional attractive force h
 as recently been inferred from experiments. We shall also discuss interact
 ions of randomly charged surfaces across an electrolyte solution and in th
 e limit of strong electrostatic correlations in the presence of multivalen
 t counterions.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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