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This article describes a unique noninvasive capability to determine the concentration (in mg/cm3) and total amount of topically applied materials in the skin (in μg/cm2 of skin surface). It is based on in vivo confocal Raman spectroscopy. A theoretical derivation is given of a general method to calculate a concentration ratio from a Raman spectrum of a material in a medium, which can be a solvent or other matrix, such as the skin. A practical implementation of the method is then presented along with a clarification of the assumptions used and applied to a quantitative analysis of the in vivo skin penetration of trans‐retinol and propylene glycol (PG). A comparison was made between the concentrations profiles of retinol and PG found in the skin and the concentrations of retinol and PG that had been applied to the skin. Determination of the amount of these materials in the skin at different timepoints after topical application also enabled a straightforward calculation of the flux of materials into the skin (in μg cm−2 h).

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Wide band gap niobium oxides are particularly important for electronic device applications. Two types of NbO powders were sintered between 300 and 1100 °C. The structural characterization of the pellets, performed by X-ray diffraction measurements and Raman spectroscopy, revealed the appearance of the NbO and T-, B-, and H-Nb2O5 polymorphs, depending on the sintering temperature. The optical characterization was complemented with absorption measurements and photoluminescence, where it was possible to identify a bandgap of 3.5 eV. A strong dependence of luminescence on the sintering temperature and therefore of the niobium oxide crystalline phases nature was observed. The influence of the morphological and structural characteristics on the dielectrical properties, at room temperature and in the low frequency range (<100 MHz), was studied. The sample with the H-Nb2O5 polymorph presents higher dielectric constant (∼55) than the samples with T- and B-Nb2O5 (∼25).