Ellipsometry of clean surfaces, submonolayer and monolayer films

Habraken, F.H.P.M.; Gijzeman, O.L.J.; Bootsma, G.A.

doi:10.1016/0167-2584(80)90063-8

Cited by 2 publications

(2 citation statements)

References 13 publications

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“…It can be seen in this figure that the experimental ⌬-⌿ signature is comprised within an envelope of values for n f between 2.3 and 3 and an oxide film thickness from 0 to 5 nm. k f was taken as zero (26). The optical constants for the Al-brass substrate were the same as those used above.…”

Section: Resultsmentioning

confidence: 99%

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

Busalmen

Sánchez

Schiffrin

1998

Appl Environ Microbiol

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Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf ) of 1.38 and a thickness (df ) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated.

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Section: Resultsmentioning

confidence: 99%

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

Busalmen

Sánchez

Schiffrin

1998

Appl Environ Microbiol

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“…The image dipole effects cannot be neglected when molecules are close to a metal surface [37]. These shortcomings can be overcome by applying the concepts of previous studies of adsorbed monolayers on flat surfaces in the context of ellipsometry [44,70,71] or differential reflectance spectroscopy [45,46]. In both cases, we consider the dyes to be arranged in square lattice.…”

Section: Microscopic Approach Versus Continuum Approachmentioning

confidence: 99%

Computational Modelling for the Optical Properties of Dye Molecules Adsorbed onto Metallic Nanoparticles

Tang¹

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The study of light scattering by particles has become fundamental and applied interests in the fields of chemistry, biology, and most importantly in physics. In this context, this thesis focuses on understanding the optical properties of dye layers adsorbed onto metallic nanoparticles (NP), which is essential for interpreting the results of plasmon-dye coupling experiments. To model such a system, Mie theory is often used to solve for the exact solution to Maxwell’s equations for spherical homogeneous and isotropic coated NP. The effects of the NP’s plasmon resonances on the optical properties of the adsorbed dye layer have been predicted using an effective medium model, where the dye-layer is treated as an isotropic layer with an effective dielectric function accounting for the dye resonance. However, this isotropic shell model is inadequate as it cannot account for the dye surface concentration and the anisotropy of the optical response of the dye layer. In this thesis, we introduce anisotropic effects within Mie theory and develop microscopic models to define effective dielectric functions which explicitly include the dye-concentration effect in the shell model. Combining anisotropic Mie theory with a concentration-dependent effective shell model allows us to form new theoretical tools to model the optical properties of adsorbed dye layers on metallic NPs of spherical shape. With this new refined effective medium model, we are then able to study shell models for elongated particles beyond the quasi-static approximation. This is implemented using the finite element method (FEM) to numerically solve Maxwell’s equations. The FEM implementation is then used to investigate how the NP’s plasmon resonance can be affected by the dye’s orientation and location on the NP’s surface. We show that the orientation and location of the dye molecules on the NP determine how strongly the plasmon resonance is shifted. The results of this work will improve our ability to accurately model the optical properties of anisotropic molecules adsorbed on metallic NPs. This is important in a number of applications including the development of localised surface plasmon resonance (LSPR) sensing and the design of plasmonic devices.

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Ellipsometry of clean surfaces, submonolayer and monolayer films

Cited by 2 publications

References 13 publications

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

Computational Modelling for the Optical Properties of Dye Molecules Adsorbed onto Metallic Nanoparticles

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