Détection photothermique et spectroscopie d'absoption de nano-objets individuels: nanoparticules métalliques, nanocristaux semiconducteurs, et nanotubes de carbone.

Abstract : During this project, we have developed a new far field optical imaging technique,
called Photothermal Heterodyne Imaging, which allows for highly sensitive, "background-free"
detection of a large variety of individual absorbing nano-objects (metallic nanoparticles with diameter
down to 1.4 nm, semiconductor nanocrystals, carbon nanotubes,. . .) . The photothermal
signal was characterized experimentally on individual gold nanoparticles. Our measurements are
in excellent agreement with analytical calculations based on an electrodynamical model. Since
the photothermal signal arising from an isolated nana-object is directly proportional to the absorbed
power, the PHI method opens new pathways towards quantitative absorption spectroscopy.
Surface Plasmon Resonance spectra of individual gold nanoparticles with diameters from 5 to 33
nm were recorded. Intrinsic size were unambiguously observed and analyzed within the frame of
Mie theory. Absorption spectroscopy of individual CdSe nanocrystals in the multiexcitonic regime
was also performed. The physical origin of the photothermal signal is discussed by confronting
the photothermal absorption spectrum and the emission spectrum of a same nanocrystal. Finally,
the structure of individual semiconducting and metallic carbon nanotubes was characterized after
analysis of their absorption spectra around the lowest optical resonances.
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Submitted on : Tuesday, September 11, 2007 - 6:59:27 AM
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Stéphane Berciaud. Détection photothermique et spectroscopie d'absoption de nano-objets individuels: nanoparticules métalliques, nanocristaux semiconducteurs, et nanotubes de carbone.. Physique [physics]. Université Sciences et Technologies - Bordeaux I, 2006. Français. ⟨tel-00123471v2⟩

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