S. Link et Ma. El-sayed, Size and temperature dependence of the plasmon absorption of colloidal gold nanoparticles, J PHYS CH B, 103(21), 1999, pp. 4212-4217
The size and temperature dependence of the plasmon absorption is studied fo
r 9, 15, 22, 48, and 99 nm gold nanoparticles in aqueous solution. The plas
mon bandwidth is found to follow the predicted behavior as it increases wit
h decreasing size in the intrinsic size region (mean diameter smaller than
25 nm), and also increases with increasing size in the extrinsic size regio
n (mean diameter larger than 25 nm). Because of this pronounced size effect
a homogeneous size distribution and therefore a homogeneous broadening of
the plasmon band is concluded for all the prepared gold nanoparticle sample
s. By applying a simple two-level model the dephasing time of the coherent
plasmon oscillation is calculated and found to be less than 5 fs. Furthermo
re, the temperature dependence of the plasmon absorption is examined. A sma
ll temperature effect is observed. This is consistent with the fact that th
e dominant electronic dephasing mechanism involves electron-electron intera
ctions rather than electron-phonon coupling.