Thermal effects on electron-phonon interaction in silicon nanostructures

Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

Noise Measurements and Noise Statistical Properties Investigations in a Stimulated Raman Scattering Microscope Based on Three Femtoseconds Laser Sources

To induce a Raman-active transition in a material, stimulated Raman scattering (SRS) spectroscopy/microscopy implementations typically rely on two pulsed laser sources. One of their limitations is that not all of the regions of Raman spectra can be investigated, so only some applications can be exploited. In this paper, the noise characterizations of a stimulated Raman scattering spectroscopy/microscopy implementation, based on the insertion of a third pulsed laser source, are provided. The merit of this system is that it is able to explore the large variety of SRS applications. In order to characterize our system, an investigation of different kinds of noises due to the laser sources and electronics sources was carried out. Firstly, the relative intensity noises of three femtosecond laser sources were measured. Secondly, noise characterizations of the detection system were carried out and our findings prove that our SRS microscope is shot noise-limited, demonstrating that the third laser source introduction is well suited and satisfies our purpose. Finally, the statistical properties of the overall image noises are analyzed and discussed. © 2022 by the authors

AMS 14C dating at CIRCE: The Major Temple in Cumae (NA – Italy)

International audienceWe present here one recent CIRCE (Centre for Isotopic Research on Cultural and Environmental Heritage)– Caserta (Italy) project on cultural heritage field, analysing several mice bones, discovered in the MajorTemple on the acropolis of Cumae (Napoli, Southern Italy). The bones were found in a vase linked to theholy context. In order to know their dating and formulate an hypothesis on their presence on the site, if itwas an accidental rodent inclusion (believed on the base of archaeological context to have occurredduring building abandonment periods (IV–V or XIII centuries AD)) or an intentional and ritual remain,the bones were 14C dated by AMS at CIRCE. The results indicate that the mice bones date to the IV centuryBC and are contemporaneous with building construction. This dating seems to exclude an accidentalrodent presence and it supports the hypothesis of Apollo veneration in the temple, based on the alreadyknown link between mice and Apollo worship rituals

Demonstration of 100 GHz electrically tunable liquid-crystal Bragg gratings for application in dynamic optical networks

We demonstrate liquid crystal-based integrated optical devices with >140GHz electrical tuning for potential applications in dynamic optical networks. Bragg wavelength tuning covering five 25GHz WDM channel spacings has been achieved with 170V (peak-to-peak) sinusoidal voltages applied across electro-patterned ITO-covered glass electrodes placed 60µm apart. This tunability range was limited only by the initial grating strength and supply voltage level. We also observed two distinct threshold behaviors that manifest during increase of supply voltage, resulting in a hysteresis in the tuning curve for both TE and TM input light