MRS Proceedings

Articles

Thermo-optical Properties of Nanoparticles and Nanoparticle Complexes Embedded in Ice: Characterization of Heat Generation and Actuation of Larger-scale Effects

2006 MRS Fall Meeting.

Hugh H. Richardsona1, Zachary N. Hickmana2, Alyssa C. Thomasa3, Martin E. Kordescha4 and Alexander O. Govorova5

a1 richards@helios.phy.ohiou.edu, Ohio University, Chemistry and Biochemistry, 231 Clippinger Laboratories, Ohio Univeristy, Dept. of Chemistry and Biochemistry, Athens, OH, 45701, United States, (740) 517-8488

a2 zh349103@ohio.edu, Ohio University, Chemistry and Biochemistry, Athens, OH, 45701, United States

a3 at137999@ohio.edu, Ohio University, Chemistry and Biochemistry, Athens, OH, 45701, United States

a4 kordesch@ohio.edu, Ohio University, Physics and Astronomy, Athens, OH, 45701, United States

a5 govorov@helios.phy.ohiou.edu, Ohio University, Physics and Astronomy, Athens, OH, 45701, United States

ABSTRACT

We have investigated the thermo-optical properties of gold NPs embedded in an ice matrix [1]. Resonant laser light of relatively weak intensity is able to melt ice with embedded Au NPs, whereas even a very intense laser beam does not melt ice alone. This comes from strong absorption in Au NPs in the regime of plasmon resonance. By recording time-resolved Raman signals, we observe the melting process and determine the threshold melting power , where is the background temperature. We also observe relatively large scattering in the threshold laser intensity that leads to melting of the ice because of the mesoscopic nature of the sample. We can understand this observation using the TEM images of NPs, showing that geometry of NP complexes varies greatly. In our recent theoretical paper we showed that the local temperature inside and around a NP complex depends strongly on its geometry, and this leads to large scattering for the measured as a function of the reduced temperature, for different complexes [2].

We recently discovered that NPs immobilized on glass surfaces can be characterized by single particle spectroscopy. Single and small NP clusters can be discriminated using the integrated intensity of the plasmon emission band. A cluster of four gold NPs has ∼ 4 times the intensity of a single gold NP. When the NPs are aggregated into a cluster then broadening of the intensity profile plot is not observed Gold NPs that are not clustered together but are found within the excitation volume will lead to a broadening of a cross sectional slice. We will use these principles to determine the amount of heat generation from single and clustered gold NPs.

[1] H. H. Richardson, Z. N. Hickman, A. O. Govorov, A. C. Thomas, W. Zhang, M. E. Kordesch, Nano Lett. (2006); DOI: 10.1021/nl060105l.

[2] A. O. Govorov, H. H. Richardson, W. Zhang, and T. Skeini, Nanoscale Res. Lett. 1, 100101 (2005).

(Received November 20 2006)

(Accepted December 11 2006)

Key Words

  • optical properties;
  • nanoscale;
  • Au
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