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Background: In vitro measurements of sunscreen products are used to assess their reliability in terms of photoprotection and photo-stability. Objective: In this study, several substrates have been fully characterized for in vitro sunscreen testing. Methods: The following different substrates have been utilised in the study: roughened PMMA plates, Transpore, Vitro-Skin, roughened quartz plate and a laboratory prepared roughened PTFE plate. The suitability of these substrates for SPF evaluation has been investigated by performing total absorbance measurements of seven sunscreen products with different SPF values produced by the same manufacturer. Results and conclusions: Application of sunscreen products on Transpore, roughened quartz plate, PMMA, PTFE and Vitro-Skin was performed efficiently. With regard to photo-stability of the substrate materials, only PMMA plate, PTFE and roughened quartz plate showed to be photo-stable after UV irradiation. With regard to SPF tests, our results indicate that Transpore, roughened quartz plate and Vitro-Skin are preferable to assess SPF values because of a better correlation between in vitro and in vivo measurements. Our study also confirms that an initial calibration must be performed for sunscreen products labelled with different SPF values. Finally, the results of our measurements demonstrate that, although a correlation between in vitro and in vivo SPF results can be established, it is never exactly 1:1.

A summary of the research performed on the optical characterization of Sc and of several lanthanides from the visible to the soft x-rays is presented. The low absorption of these materials mainly below the O 2,3 edge (L 2,3 edge for Sc) turns them promising materials for the realization of multilayer mirro rs in a spectral range in which most materials in nature absorb strongly. Thin-film samples with several thicknesses of the target material were deposited by evaporation over thin-film substrates in UHV, and their transmittance was measured in situ. A wide spectral range of direct characterization, along with extrapolations to longer and shorter wavelengths either using literature data (when available) or model predictions, enabled the development of consistent optical constants over the whole spectrum. An assortment of consistency sum rules has been used, and it was found that each of them highlights a gi ven spectral range, which may help evaluate the consistency of each part of the combined spectrum. Keywords: Extreme Ultraviolet, far ultraviolet, optical constants, absorption filters, multilayers, optical properties of thin films

The extinction coefficient of Pr, Eu and Tm thin films prepared by evaporation in ultra high vacuum has been obtained in the spectral ranges 4 − 1600, 8.3 – 1400 and 10 – 1400 eV, respectively. These data were calculated from experimental values of the transmittance of the films performed in situ, which means that the samples were not exposed to the atmosphere before and during their characterization. Several films of increasing thickness were deposited onto grids coated with a thin C support film. The results show that Pr, Eu and Tm, similar to other lanthanides, have a lowabsorption band right below the O2,3 edge onset, with lowest absorption measured at about 16.9, 16.7 and 23 eV, respectively. Therefore, these materials are promising for filters and multilayer coatings in the energy range below O2,3 edge in which materials typically present a strong absorption. In the cases of Pr and Eu the f sum rule was applied to the extinction coefficient data in the whole spectrum, that included the current data along with those of the literature and extrapolations. The obtained values of the number of electrons contributing to the optical properties of the materials were close to predictions, which shows the consistency of current data. In the case of Pr, the real part of the index of refraction was also calculated through the Kramers-Kronig analysis, and the consistency of the results was assessed by means of the inertial sum rule.

The optical constants of Ce films were obtained in the 6-1200 eV range from transmittance measurements obtained at room temperature. Thin films of Ce were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Ce films were deposited onto grid-supported, thin C films. Transmittance measurements of various film thicknesses were used to obtain the extinction coefficient k of Ce films at each individual photon energy investigated. The refractive index n of Ce was calculated with the Kramers-Kronig analysis using the current k data, which were extended toward smaller and larger energies with available data from literature and extrapolations. Ce has a low-absorption band right below O-2,O-3 edge, with lowest absorption at 16.1 eV. This makes Ce a promising material for the development of new filters and multilayer coatings below Ce O-2,O-3 edge, in which few developments have been performed due to the lack of low-absorption materials. A good consistency of the data was evaluated through f and inertial sum rules.

"The optical constants of Eu films were obtained in the 8.3-1400 eV range from transmittance measurements performed at room temperature. Thin films of Eu were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Eu films were deposited onto grids coated with a thin C support film. The refractive index n of Eu was calculated using the Kramers-Kronig analysis. Data were extrapolated both on the high- and low-energy sides by using experimental and calculated extinction coefficient values available in the literature. Eu, similar to other lanthanides, has a low-absorption band just below the O-2,O-3 edge onset; the lowest absorption was measured at about 16.7 eV. Therefore, Eu is a promising material for filters and multilayer coatings in the energy range below the O-2,O-3 edge in which materials typically have a strong absorption. The consistency of the composite optical constants was tested with the f and inertial sum rules and found to be good."

"The optical constants of Pr films were obtained in the 4-1600 eV range from transmittance measurements performed at room temperature. Thin films of polycrystalline Pr were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Pr films were deposited onto grids coated with a thin, C support film. Transmittance measurements were used to obtain the optical extinction coefficient k of Pr films in the 4-1600 investigated photon energy range. The refractive index n of Pr was calculated using the Kramers-Kronig analysis. Data were extrapolated both on the high and low-energy sides by using experimental and calculated extinction coefficient data available from the literature. Pr, similar to other lanthanides, has a low-absorption band right below the O-2,O-3 edge onset; the lowest absorption was measured at about 17 eV. Therefore, Pr is a promising material for filters and multilayer coatings in the energy range below O-2,O-3 edge in which most materials have a strong absorption. A good consistency of the data were obtained through f and inertial sum rules. (C) 2008 American Institute of Physics."

Within a National Project on nanotechnologies, a Micro-Exposure Tool (MET) for projection lithography at 14.4 nm, based on a laser-produced plasma source, is being developed at the Frascati ENEA Center. The choice of this “exotic” wavelength is due to the higher efficiency of a Debris Mitigation System (DMS) working in the interval of approximately 14 nm < < 15 nm. It has to be noted that Mo/Si multilayer mirrors (MLM) can still have a high reflectivity also at these wavelengths. The solid-tape-target laser-generated plasma is driven by a XeCl excimer laser, with an optimized intensity of about 3 1010 W/cm 2 , generating an extreme ultraviolet (EUV) source with a diameter of about 0.2 mm. Clearly, this kind of source emits a lot of debris (both atomic and particulate types) and the 7-cm-far collector mirror must be protected against them. The paper is mostly devoted to the accurate and systematic study of these debris and to their reduction. The results of mitigation efficiency obtained with a DMS prototype are very encouraging and lead to the design and patenting of its improved version. Keywords: Extreme ultraviolet, EUV, laser-produced plasma, lithography, EUVL , debris, micro-exposure tool, MET, X-rays.

An innovative sensor with a spectral response equivalent to the erythemal action curve for ultraviolet total effective irradiance measurements is presented. Optical and sensor components have been selected after the characterization of different samples. The design is based on an innovative interferential filter, which has been realized and tested. A first prototype has been assembled and characterized. Our measurements demonstrate the feasibility and potential of this instrument. (c) 2007 Optical Society of America.

B4C optical coating represents, together with Ir, Pt, SiC, one of best choice for high reflectance in the extreme ultraviolet region (EUV 160-30 nm). This material is also used in multilayer for soft X-ray applications, such as Si/B4C or W/B4C, or as interlayer in Mo/Si multilayer to avoid interdiffusion also because of its high thermal stability. Our work concerns on B4C thin films deposited on Si [100] substrates by means of three different deposition techniques: RF plasma magnetron sputtering, e-beam evaporation, pulsed laser ablation (PLD). We performed reflectance vs incidence angle measurements from 5 nm to 152 nm on different samples deriving the optical constants with a least-square fitting method. Complete films characterization have been carried out with compositional (XPS), structural (XRD) and morphological (AFM, SEM) analyses.

The research on rare earths conducted by the current team addresses in this proceeding the transmittance measurement of Ce films. Several thin films of Ce were deposited by evaporation in ultra high vacuum (UHV) conditions and their transmittance was measured in situ in the 6-1,200 eV spectral range. Ce films were deposited onto grids coated with a thin, C support film. Transmittance measurements were used to obtain the extinction coefficient of Ce films at each individual photon energy investigated. Literature data for Ce films had been restricted to some parts of the current range, with various experimental data at the strong N edge, a single set of data at the M edge, and no data at the O edge. The energy range here investigated provides data encompassing M, N, and O edges of Ce, and this data set is extended towards smaller energies with experimental data and towards larger energies with semi-empirical data and calculations. Ce, as has been measured with other lanthanides, has a low-absorption band right below the O edge, with lowest absorption at 16.1 eV. This makes Ce a promising material for filters and multilayer coatings in this spectral range, in which few developments have been performed due to the lack of low absorption materials. The f1 sum-rule was applied to the extinction coefficient data in the whole spectrum that included the current data along with those of the literature, resulting in a value close to predictions, which shows the consistency of the current data.

The transmittance of thin films of Yb deposited by evaporation in ultra high vacuum (UHV) conditions have been investigated in the 23-1,700 eV spectral range. Transmittance measurements were performed in situ on Yb films deposited over grids coated with a thin, C support film. Transmittance measurements were used to obtain the extinction coefficient of Yb films at each individual photon energy investigated. The energy range investigated encompasses M, N, and O edges of Yb. The current results, along with data in the literature, show that Yb has an interesting low-absorption band in the ~12-24 eV range. The promising characteristics of Yb as a filter material in this region requires the development of a protection material due to the reactivity of Yb under normal atmosphere. The low absorption of Yb in the above range makes it also a candidate for a component of multilayer coatings in a spectral region in which few developments have been performed due to the lack of low absorption materials. The f1 sum-rule was applied to extinction coefficient data in the whole spectrum that included the current data along with those of the literature, resulting in a value of 70.26, which is close to the expected value of 69.32.

B4C optical coating represents, together with Ir, Pt, SiC, one of best choice for high reflectance in the extreme ultraviolet region. This material is also used combined with others materials in multilayer such as Si/B4C or as interlayer in Mo/Si multilayer to avoid interdiffusion. In this study we have performed optical, compositional and structural analyses for thin film of B4C deposited by means of magnetron sputtering and on preliminary samples deposited by e-beam evaporation. Here we report reflectivity measurements and the derived optical constants of B4C in the 400-1500 angstrom region. (c) 2006 Elsevier Ltd. All rights reserved.

Optical constants of SiC thin films deposited with RF magnetron sputtering have been derived in the VUV. The films have been deposited with different parameters resulting in various C/Si ratios. Reflectance measurements have been made with a dedicated facility in the range 300–1300 Ǻ. Index of refraction and absorption coefficient have been derived by fitting the reflectance data with the calculated ones.

Long UV radiation exposure can result in damages of biological tissues, as burns, skin aging, erythema and even melanoma cancer. In the past years an increase of melanoma cancer has been observed and associated to the atmospheric ozone deployment. Attendance of sun tanning unit centers has become a huge social phenomena, and the maximum UV radiation dose that a human being can receive is regulated by law. On the other side, UV radiation is largely used for therapeutic and germicidal purposes. In all these areas, spectroradiometer and radiomenter are needed for monitoring UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm) irradiance. We have selected some commercial photodiodes which can be used as solid state detectors in these instruments. We have characterized them by measuring their absolute spectral response in the 200 - 400 nm spectral range.

We report numerical and experimental results on the optical response of transparent metal coated wedges arrays for plasmonic nanofocusing. Light normally impinging from the dielectric side is coupled to Surface Plasmon Polaritons (SPPs) at the oblique metal-air interfaces. A dielectric phase shifter has been implemented in the structure in order to allow constructive interference of SPPs at the wedge apex. Finite Elements simulations were used to design the system. Focused Ion Beam (FIB) milling, chemical etching and replica molding were used for the fabrication. NSOM and Raman measurements demonstrate that plasmonic nanofocusing actually takes place in the structure.

Lead zirconate titanate (PZT) thin films were deposited by rf magnetron sputtering on Pt/Ti/SiO 2//Si, Au/Ti/SiO2//Si, ITO//glass electrodes and on Si (100) substrates. As deposited films show large excesses of Pb and O and contain different Pb oxides. Annealing treatments in air at 650 and 750 °C carried out in a preheated muffle furnace lead to a decrease of Pb and O content and to formation of the perovskite phase via an intermediate nanocrystalline pyrochlore phase. Phase pure perovskite films are obtained on Pt and ITO electrodes by annealing at 750 °C for ~10 min, while for the same treatment significant amounts of pyrochlore remained on Au electrodes and on Si substrates.

The fabrication, characterization and functionalization of periodically patterned nanoporous gold layers is presented. The material shows plasmonic properties in the near infrared range, with excitation and propagation of surface plasmon polaritons. Functionalization shows a marked enhancement in the optical response in comparison with evaporated gold gratings, due to a great increase of the active surface. Due to its superior response, nanoporous gold patterns appear promising for the realization of compact plasmonic platforms for sensing purposes.

Reflectance versus incidence angle measurements have been performed from 5 to 152 nm on samples of SiC with a different C/Si ratio deposited with rf magnetron sputtering. The optical constants of the material at different wavelengths have been determined by using a curve-fitting technique of reflectance values versus incidence angle. Complementary measurements of the incident beam polarization, film thickness, surface roughness, and stoichiometry were performed to complete the analysis of the samples.

We demonstrate the generation of far-field propagating optical beams with a desired orbital angular momentum by using a smooth optical mode transformation between a plasmonic vortex and free space Laguerre-Gaussian modes. This is obtained by means of an adiabatically tapered gold tip surrounded by a spiral slit. The proposed physical model, backed up by the numerical study, brings about an optimized structure which is fabricated by using highly reproducible secondary electron lithography technique. Optical measurements of the structure excellently agree with the theoretically predicted far-field distributions. This architecture provides a unique platform for a localized excitation of plasmonic vortices followed by its beaming., Comment: Nano Letters, 2016

Here, we propose an easy and robust strategy for the versatile preparation of hybrid plasmonic nanopores by means of controlled deposition of single flakes of MoS2 directly on top of metallic holes. The device is realized on silicon nitride commercial membranes and can be further refined by TEM or FIB milling to achieve the passing of molecules or nanometric particles through a pore. Importantly, we show that the plasmonic enhancement provided by the nanohole is strongly accumulated in the 2D nanopore, thus representing an ideal system for single-molecule sensing and sequencing in a flow-through configuration. Here, we also demonstrate that the prepared 2D material can be decorated with metallic nanoparticles that can couple their resonance with the nanopore resonance to further enhance the electromagnetic field confinement at the nanoscale level. This method can be applied to any gold nanopore with a high level of reproducibility and parallelization; hence, it can pave the way to the next generation of solid-state nanopores with plasmonic functionalities. Moreover, the controlled/ordered integration of 2D materials on plasmonic nanostructures opens a pathway towards new investigation of the following: enhanced light emission; strong coupling from plasmonic hybrid structures; hot electron generation; and sensors in general based on 2D materials. Nanopore

We investigate an architecture where a plasmonic vortex excited in a gold surface propagates on an adiabatically tapered magnetic tip and detaches to the far-field while carrying a well-defined optical angular momentum. We analyze the out-coming light and show that, despite generally high losses of flat magnetic surface, our 3D structure exhibits high energy throughput. Moreover, we show that once a magneto-optical activity is activated inside the magnetic tip a modulation of the total power transmittance is possible.

Plasmonic nanopores are the subject of extensive investigations as a potential platform to enable efficient optical readout in translocation experiments with biomolecules such as DNA and proteins. They allow for the engineering of electromagnetic fields at the nanoscale, which are typically used to enhance the emission efficiency of fluorescent molecules. Their features make them suitable for detection strategies based on the energy transfer between translocating molecules and the nanopore itself. Here, we carry out an optical experiment to show that a handful of diffusing dyes acting as donors can exchange energy via F\"orster-resonance energy transfer (FRET) with a gold nanopore functionalized with dyes behaving as acceptors. The FRET pair is composed of ATTORho6G (donor) and Alexa610 (acceptor). To perform this proof-of-concept experiment, we use a gold nanopore with a diameter of 80 nm, prepared on a ${\text{Si}}_{3}{\text{N}}_{4}$ membrane. We observe that the presence of the acceptors on the walls of the nanopore reduces the lifetime of the diffusing donors. In addition, we observe that the presence of the acceptors reduces the fluorescence signal on the donor detection channel and increases the fluorescence signal on the acceptor detection channel. The combination of these three effects gives us enough evidence to claim that the diffusing donors exchange energy with the functionalized nanopore via FRET, despite the relatively large size of the nanopore. The FRET efficiency of the process is found to be of the order of $30\mathrm{%}$, which is in fairly good agreement with a theoretical value obtained using a simplified model.

We fabricate a plasmonic nanoslot that is capable of performing enhanced single molecule detection at 10 muM concentrations. The nanoslot combines the tiny detection volume of a zero-mode waveguide and the field enhancement of a plasmonic nanohole. The nanoslot is fabricated on a bi-metallic film formed by the sequential deposition of gold and aluminum on a transparent substrate. Simulations of the structure yield an average near-field intensity enhancement of two orders of magnitude at its resonant frequency. Experimentally, we measure the fluorescence stemming from the nanoslot and compare it with that of a standard aluminum zero-mode waveguide. We also compare the detection volume for both structures. We observe that while both structures have a similar detection volume, the nanoslot yields a 25-fold fluorescence enhancement.

We fabricated hybrid metal-dielectric nanoantennas and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence measurements. We characterized the fluorescence enhancement, as well as the lifetime and detection volume reduction for each wavelength. We observe that the hybrid metal-dielectric nanoantennas behave as enhanced Zero Mode Waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of microM. However, a wavelength blue-shift of 40 nm dramatically decreases the performance of the nanoantennas. We compared their behavior with that of a golden ZMW, and we verified that the dielectric silicon layer improves the design. We interpreted the experimental observations with the help of numerical simulations. In addition, the simulations showed that the field enhancement of the structure highly depends on the incoming beam: tightly focused beams yield lower field enhancements than plane-waves.