A novel refractive-index detection scheme used for capillary electrophoresis detection, based on the interference of two retroreflected beams from the outer surface of a capillary tube illuminated by a focused laser beam, is described. A theoretical description and experimental measurement of the intensity profile of the interference fringe pattern in the detection plane are presented. The factors that limit the sensitivity of the proposed refractive-index detection scheme are discussed and compared with the transmitted beam interference and backscatter-based refractive-index detection configurations. The proposed refractive-index detector was used successfully for detection of capillary electrophoresis separations of saccharose, maltose, and lactose with a capillary tube of 50-mum inner diameter and a simple experimental setup.
Modulated thermoreflectance microscopy is applied to a complete thermal characterization of a thin film of gold (78 nm) or YBaCuO (300 nm) on a LaAlO3 substrate. The phase profile, measured at several modulation frequencies covering an appropriate range, is fitted with a rigorous thermal diffusion model. This leads to a simultaneous estimation of the thermal diffusivities of the film and the substrate, as well as of the thermal film/substrate boundary resistance. The estimated values for the gold film sample are, respectively, 4.3×10−6 m2 s−1 (substrate diffusivity), 1.0×10−4 m2 s−1 (film diffusivity), and 1.0×10−8 m2 KW−1 (thermal boundary resistance), while for the thermally anisotropic YBaCuO film sample are, 4.1×10−6 m2 s−1, 3.5×10−6 m2 s−1 (in-plane diffusivity), and 8.0×10−8 m2 KW−1, respectively.
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