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CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1669
DTSTART:20100211T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T131402Z
LAST-MODIFIED:20100128T190810Z
LOCATION:5310 Chamberlin
SUMMARY:Biomimetic Color Detection Using Chromophore-Nanotube Hybrid D
 evices\, R. G. Herb Condensed Matter Seminar\, Dr. Francois Leonard & 
 Dr. Andy Vance\, Sandia National Laboratory\, CA
DESCRIPTION:Phototransduction plays a central role in key natural proc
 esses such as vision and photosynthesis. For these processes\, natural
  evolution has found exquisite solutions that optimize efficiency\, co
 mpactness\, and self-healing. While  researchers have long tried to su
 pplant nature's successes using solid-state approaches\, our ability t
 o convert optical radiation to electrical signals with nanoscale preci
 sion still remains in its infancy. An alternative to solid-state appro
 aches is one that more closely mimics natural processes by integrating
  chemical or biological materials with solid-state materials. To this 
 end\, we present a nanoscale color detector based on a single-walled c
 arbon nanotube functionalized with azobenzene chromophores\, where the
  chromophores serve as photoabsorbers and the nanotube as the electron
 ic read-out. By synthesizing chromophores with specific absorption win
 dows in the visible spectrum and anchoring them to the nanotube surfac
 e\, we demonstrate the controlled detection of visible light of low in
 tensity in narrow ranges of wavelengths. Our measurements suggest that
  upon photoabsorption\, the chromophores isomerize from the ground sta
 te trans configuration to the excited state cis configuration\, accomp
 anied by a large change in dipole moment\, changing the electrostatic 
 environment of the nanotube. We will also present our all-electron ab 
 initio calculations that are used to study the chromophore-nanotube hy
 brids and show that the chromophores bind strongly to the nanotubes wi
 thout disturbing the electronic structure of either species. Calculate
 d values of the dipole moments support the notion of dipole changes as
  the optical detection mechanism.<br>
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URL:https://www.physics.wisc.edu/events/?id=1669
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