Ellipsometry at the Nanoscale

Spectroscopic Ellipsometry for Operando Monitoring of (De)Lithiation-Induced Phenomena on LiMn2O4 and LiNi0.5Mn1.5O4 Electrodes

“…Therefore, the general procedure is to parametrize the optical constants with a simpler analytic expression (based on oscillators) once the shape is determined using the Bspline layer. 32 From the reflected Ψ and Δ signals of the LMO stack at each photon energy, the complex dielectric function (ε…”

“…From the three main EMA mixing methods (Linear, Bruggeman and Maxwell-Garnet), Bruggeman is adopted for its symmetry with respect to interchanging components of comparable volume fractions. 32 The model includes a layer with the obtained optical constants of LiMn 2 O 4 (L1) and a layer of delithiated Mn 2 O 4 (L2) (>4.0 V vs Li + /Li) with a fixed thickness of L2 = 0 nm (0% EMA of L2, 100% EMA of L1) at the beginning of the delithiation. Figure 7 summarizes the results of the thickness fitting over time during repeated cyclic voltammetry in the range 3.6-4.4 V vs Li + /Li with operando ellipsometry measurements.…”

Investigating the void structure of the polyamide active layers of thin-film composite membranes

“…The particular way in which the refractive index is a function of the light wavelength is referred to as "dispersion formulae". "Cauchy" formulae is the simplest dispersion used, and it is particularly suitable to describe the optical properties of weakly absorbing materials [36] such as various transparent polymers [37][38][39]. Therefore, our complete model used to fit the ellipsometric data consisted of a 3-layer structure having a Cauchy layer at the surface representing the active layer, an intermediate 2-nm silicon dioxide layer [40], and 1 mm silicon substrate.…”

“…Woollam Co.). Cauchy dispersion formulae [36] were used to describe the optical properties of the polymer layer by selecting the appropriate option in the WVASE s software whose database also contains the well-known optical constants for silicon and silicon dioxide. The refractive index and thickness of the active layers were obtained with the WVASE s software by fitting the data to the model until a minimized mean squared error of less than 20 was reached.…”

Optical Properties of Complex Oxide Thin Films Obtained by Pulsed Laser Deposition

“…It can be said that it starts with the "wave theory of light" of Robert Hooke followed by the contribution of many scientists: Christian Huygens, Augustin-Jean Fresnel, Michael Faraday, James Clerk Maxwell, etc. In 1902, Paul Drude published the "Polarization" chapter in the book "The Theory of Optics," which still serves as a modern introduction to the study of polarized light and ellipsometry [7]. Ellipsometry developed slowly for long time after the Drude ellipsometer, using a single wavelength in the 1960s.…”