| Abstract
| - The size and temperature dependence of the plasmon absorption is studied for 9, 15, 22, 48, and 99 nm goldnanoparticles in aqueous solution. The plasmon bandwidth is found to follow the predicted behavior as itincreases with decreasing size in the intrinsic size region (mean diameter smaller than 25 nm), and alsoincreases with increasing size in the extrinsic size region (mean diameter larger than 25 nm). Because of thispronounced size effect a homogeneous size distribution and therefore a homogeneous broadening of the plasmonband is concluded for all the prepared gold nanoparticle samples. By applying a simple two-level model thedephasing time of the coherent plasmon oscillation is calculated and found to be less than 5 fs. Furthermore,the temperature dependence of the plasmon absorption is examined. A small temperature effect is observed.This is consistent with the fact that the dominant electronic dephasing mechanism involves electron−electroninteractions rather than electron−phonon coupling.
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