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The challenge of characterizing thin films involves extracting t, n(λ) and k(λ) of the film from the measurement of R(λ) and/or T(λ). This can be achieved by combining the Forouhi–Bloomer dispersion equations for n ( λ ) and k ( λ ) with the Fresnel equations for the reflection and transmission of light at an interface [ 21 ] to obtain ...
The heat transfer coefficient is often calculated from the Nusselt number (a dimensionless number). There are also online calculators available specifically for Heat-transfer fluid applications. Experimental assessment of the heat transfer coefficient poses some challenges especially when small fluxes are to be measured (e.g. < 0.2 W/cm 2). [1] [2]
The colors of a soap bubble are determined by the optical path length through the thin soap film in a phenomenon called thin-film interference. Optical path length (OPL) is the product of the geometric length d of the path light follows through a system, and the index of refraction of the medium through which it propagates, [40] =.
Epitaxial thin films may experience stresses from misfit strains between the coherent lattices of the film and substrate, and from the restructuring of the surface triple junction. [27] Thermal stress is common in thin films grown at elevated temperatures due to differences in thermal expansion coefficients with the substrate. [28]
The basic form of a 2-dimensional thin film equation is [3] [4] [5] = where the fluid flux is = [(+ ^) + ^] +, and μ is the viscosity (or dynamic viscosity) of the liquid, h(x,y,t) is film thickness, γ is the interfacial tension between the liquid and the gas phase above it, is the liquid density and the surface shear.
FreeSnell is a stand-alone computer program that implements the transfer-matrix method, including more advanced aspects such as granular films. Thinfilm is a web interface that implements the transfer-matrix method, outputting reflection and transmission coefficients, and also ellipsometric parameters Psi and Delta.
The main advantages of the 3ω-method are minimization of radiation effects and easier acquisition of the temperature dependence of the thermal conductivity than in the steady-state techniques. Although some expertise in thin film patterning and microlithography is required, this technique is considered as the best pseudo-contact method available.
The film temperature is often used as the temperature at which fluid properties are calculated when using the Prandtl number, Nusselt number, Reynolds number or Grashof number to calculate a heat transfer coefficient, because it is a reasonable first approximation to the temperature within the convection boundary layer.