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SUMMARY:The Color of Brownian Motion
DTSTART:20130614T141500
DTSTAMP:20260428T002202Z
UID:cd448d3f1c3bbfae119f14c58e8efad3255f2198b6bd3257904ed7ea
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Sylvia Jeney\, Laboratoire de Physique de la Matière Comp
 lexe - LPMC\, EPFL\nObservation of the Brownian motion of a small probe in
 teracting with its environment is one of the main strategies to characteri
 ze soft matter. Initially\, the particle is driven by rapid collisions wit
 h the surrounding solvent molecules\, referred to as thermal noise. Later\
 , the friction between the particle and the viscous solvent damps its moti
 on. Conventionally\, thermal force is taken to be characterized by a Gauss
 ian white noise spectrum. The friction is assumed to be given by the Stoke
 s drag\, suggesting that motion is overdamped at long times\, when inertia
  becomes negligible.\nRecently\, we measured the noise spectrum of the the
 rmal forces by tracking with high resolution a single micron-sized sphere 
 suspended in a fluid\, and confined by a stiff optical trap. Coupling betw
 een sphere and fluid gives rise to hydrodynamic memory and a resonance\, e
 quivalent to a colored peak in the power spectral density of the sphere’
 s thermal fluctuations. Our results reveal that motion is not overdamped\,
  and the particle-fluid-trap system can be considered a nanomechanical res
 onator. By bridging novel theoretical insights to model experiments with u
 nprecedented accuracy\, we are aiming at developing a novel type of multid
 imensional\, time-resolved\, near-field sensor for the study and manipulat
 ion of soft and living matter.
LOCATION:PH L1 503 http://plan.epfl.ch/?room=PHL1503
STATUS:CONFIRMED
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