1 research outputs found
Brewster-Angle Variable Polarization Spectroscopy of Colloidal Au-Nanospheres and -Nanorods at the Silicon Surface
Colloidal Au-nanospheres and -nanorods were chemically
synthesized from chloroauric acid containing solutions and adsorbed
to hydrogen-terminated p-Si(111) surfaces. A comparative analysis
of the respective plasmon resonance modes, in solution and at the
silicon surface, was carried out by in situ optical transmission and
surface reflection techniques. In solution, the absorbance was determined
by VIS transmission spectroscopy and compared to Mie theory as well
as finite difference time domain calculations. At the p-Si(111) surface,
the reflectance was analyzed for the first time by Brewster-angle
variable polarization spectroscopy (BA-VPS) and discussed in terms
of anisotropic uniaxial thin-film properties. With BA-VPS, the strengths
of parallel and orthogonal electric field components of the incident
wave can be varied relative to the surface plane. Consequently, opposite
changes of transverse and longitudinal resonance strengths are detected
upon gradually incremented light polarization angles. Model considerations
confirm that spherical and elongated particles can thereby be distinguished.
The influence of particle–surface interaction and the dielectric
environment is finally discussed