Richardson, H. H. and Hickman, Z. N. and Govorov, A. O. and Thomas, A. C. and Zhang, W and Kordesch, M. E. (2006) Thermooptical properties of gold nanoparticles embedded in ice: Characterization of heat generation and melting. NANO LETTERS, 6 (4). pp. 783-788.
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Official URL: http://dx.doi.org/10.1021/nl060105l
We investigate the system of optically excited gold NPs in an ice matrix aiming to understand heat generation and melting processes at the nanoscale level. Along with the traditional fluorescence method, we introduce thermooptical spectroscopy based on phase transformation of a matrix. With this, we can not only measure optical response but also thermal response, that is, heat generation. After several recrystallization cycles, the nanoparticles are embedded into the ice film where the optical and thermal properties of the nanoparticles are probed. Spatial fluorescence mapping shows the locations of Au nanoparticles, whereas the time-resolved Raman signal of ice reveals the melting process. From the time-dependent Raman signals, we determine the critical light intensities at which the laser beam is able to melt ice around the nanoparticles. The melting intensity depends strongly on temperature and position. The position-dependence is especially strong and reflects a mesoscopic character of heat generation. We think that it comes from the fact that nanoparticles form small complexes of different geometry and each complex has a unique thermal response. Theoretical calculations and experimental data are combined to make a quantitative measure of the amount of heat generated by optically excited Au nanoparticles and agglomerates. The information obtained in this study can be used to design nanoscale heaters and actuators.
|Subjects:||Analytical Science > Nanotechnology for sensing and actuating|
Physical Science > Nano objects
|Deposited On:||22 Jan 2009 09:46|
|Last Modified:||26 Mar 2009 14:49|
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