Search

This study deals with numerical simulations to optimize the parameters of the Dark Filed Z-scan (DFZ-scan) in a microscopic configuration for third-order nonlinear (NL) refraction measurements into thin films. The method allows dynamic, transparent, nonlinear phase shifts to be clearly visible. The simulations of such images are obtained for very low-induced refractive indices. Darkfield illumination requires blocking out of the central light which ordinarily passes through and around (surrounding) the NL specimen. A table to approximate circular aperture stop size versus magnification will be given depending on the focusing lens into the tested material. [ABSTRACT FROM AUTHOR]

The single-beam Z -scan thermal lens technique is conducted to evaluate the fluorescence quantum yield of various solutions in the case of high-moderate absorption, considering both scenarios: solutions with substantial fluorescence and solutions with high thermal efficiency but low fluorescence. An analytical calculation is performed to determine the uncertainties associated with the random errors introduced by optical detectors. The results reveal that solutions with low fluorescence lead to a significant error, whereas higher fluorescence can help in decreasing the uncertainty. Additionally, the issue of random errors arising when multiple measurements are needed to accurately estimate the fluorescence of a solution will be discussed in different situations.

Surface-enhanced Raman scattering (SERS) is a powerful and sensitive technique for the detection of fingerprint signals of molecules and for the investigation of a series of surface chemical reactions. Many studies introduced quantitative applications of SERS in various fields, and several SERS methods have been implemented for each specific application, ranging in performance characteristics, analytes used, instruments, and analytical matrices. In general, very few methods have been validated according to international guidelines. As a consequence, the application of SERS in highly regulated environments is still considered risky, and the perception of a poorly reproducible and insufficiently robust analytical technique has persistently retarded its routine implementation. Collaborative trials are a type of interlaboratory study (ILS) frequently performed to ascertain the quality of a single analytical method. The idea of an ILS of quantification with SERS arose within the framework of Working Group 1 (WG1) of the EU COST Action BM1401 Raman4Clinics in an effort to overcome the problematic perception of quantitative SERS methods. Here, we report the first interlaboratory SERS study ever conducted, involving 15 laboratories and 44 researchers. In this study, we tried to define a methodology to assess the reproducibility and trueness of a quantitative SERS method and to compare different methods. In our opinion, this is a first important step toward a "standardization" process of SERS protocols, not proposed by a single laboratory but by a larger community.