The plasmonic behavior of size-selected supported silver clusters is studied by surface second harmonic generation spectroscopy for the first time. A blue shift of ∼0.2 eV in the plasmon resonance is observed with decreasing cluster size from Ag55 to Ag9. In addition to the general blue shift, a nonscalable size-dependence is also observed in plasmonic behavior of Ag nanoclusters, which is attributed to varying structural properties of the clusters. The results are in quantitative agreement with a hybrid theoretical model based on Mie theory and the existing DFT calculations.
Well defined thin molecular films of 2,2'-dihydroxy-1,1'binaphthyl (binol) molecules at coverages between 5 × 10(15) molecules per cm(2) and 10(17) molecules per cm(2) on thin glass (BK7) substrates were investigated under ultra-high-vacuum (UHV) conditions. Second-Harmonic-Generation Optical-Rotatory-Dispersion measurements (SHG-ORD) were performed using a dedicated spectroscopic setup which allows for the determination of the rotation angle of the SH-signal of two enantiomers. Rotation angles of up to 38 degrees were measured. The chirality of the two enantiomers has been studied at 674 nm (337 nm resonance wavelength) in the transmission mode. Coverage dependent orientation evolution of binol molecular films was revealed by precise monitoring of the surface coverage while performing SHG-ORD experiments. We show that the molecules reach their final orientation at a surface coverage of 5 × 10(16) molecules per cm(2). From the obtained experimental data the ratio of chiral and achiral susceptibility components could be calculated and was observed to change with coverage.
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