Probing ozone effects on European hornbeam (Carpinus betulus L. and Ostrya carpinifolia Scop.) leaf water content through THz imaging and dynamic stomatal response.

We investigated the impact of ozone exposure on Hornbeam using a novel dual approach based on Terahertz (THz) imaging in a free-air ozone exposure experiment (three ozone levels: ambient; 1.5 times ambient; twice ambient). The research aims at unraveling the physiological responses induced by elevated ozone levels on water dynamics.

Strongly Fluorescent Blue-Emitting LaO: Bi Phosphor for Latent Fingerprint Detection.

Blue-emitting bismuth-doped lanthanum oxide (LaO: Bi) with various concentrations of Bi was synthesized using the sol-gel combustion method and used for visualization of latent fingerprints (LFPs). An X-ray diffraction (XRD) study revealed the hexagonal structure of the phosphors and total incorporation of the bismuth in the LaO matrix. Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to study the morphology and the relative vibrations of the synthesized samples.

Terahertz imaging for non-invasive classification of healthy and cimiciato-infected hazelnuts.

The development of new non-invasive approaches able to recognize defective food is currently a lively field of research. In particular, a simple and non-destructive method able to recognize defective hazelnuts, such as cimiciato-infected ones, in real-time is still missing. This study has been designed to detect the presence of such damaged hazelnuts.

Polarization Control in Integrated Graphene-Silicon Quantum Photonics Waveguides.

We numerically investigated the use of graphene nanoribbons placed on top of silicon-on-insulator (SOI) strip waveguides for light polarization control in silicon photonic-integrated waveguides. We found that two factors mainly affected the polarization control: the graphene chemical potential and the geometrical parameters of the waveguide, such as the waveguide and nanoribbon widths and distance. We show that the graphene chemical potential influences both TE and TM polarizations almost in the same way, while the waveguide width tapering enables both TE-pass and TM-pass polarizing functionalities.

Eu-Doped Pyrochlore Crystal Nano-Powders as Fluorescent Solid for Fingerprint Visualization and for Anti-Counterfeiting Applications.

Undoped YSnO and Eu doped YSnO samples with doping concentrations 7%, 8%, 9%, and 10% are successfully synthesized by the co-precipitation method. A complete structural, morphological, and spectroscopic characterization is carried out. XRD measurements reveal that samples crystallize in the pure single pyrochlore phase and Eu ions occupy sites with D symmetry.

RE-Based Inorganic-Crystal Nanofibers Produced by Electrospinning for Photonic Applications.

Electrospinning is an effective and inexpensive technique to grow polymer materials in nanofiber shape with exceptionally high surface-area-to-volume ratio. Although it has been known for about a century, it has gained much interest in the new millennium thanks to its low cost and versatility, which has permitted to obtain a large variety of multifunctional compositions with a rich collection of new possible applications. Rare-earth doped materials possess many remarkable features that have been exploited, for example, for diode pumped bulk solid-state lasers in the visible and near infrared regions, or for biomedical applications when grown in nanometric form.

Temperature-Dependent Stimulated Emission Cross-Section in Nd:YLF Crystal.

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the F multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K.

Enhanced Piezoelectricity of Electrospun Polyvinylidene Fluoride Fibers for Energy Harvesting.

Piezoelectric polymers are promising energy materials for wearable and implantable applications for replacing bulky batteries in small and flexible electronics. Therefore, many research studies are focused on understanding the behavior of polymers at a molecular level and designing new polymer-based generators using polyvinylidene fluoride (PVDF). In this work, we investigated the influence of voltage polarity and ambient relative humidity in electrospinning of PVDF for energy-harvesting applications.

Super-quadratic upconversion luminescence among lanthanide ions.

We explore the arguably most fundamental aspect of energy-transfer upconversion (ETU), namely the dependence of upconversion luminescence from a higher-energy level, following ETU excitation from a metastable lower-energy level, on direct luminescence from that metastable level. We investigate ETU among neighboring Nd ions in single crystals of GdVO and LaSc(BO) with different doping concentrations by measuring, after short-pulse laser excitation with different pump energies, the infrared luminescence decay from the metastable F level and the yellow upconversion luminescence decay from the G level. We observe a highly super-quadratic dependence of upconversion on direct luminescence intensity.

THz Water Transmittance and Leaf Surface Area: An Effective Nondestructive Method for Determining Leaf Water Content.

Water availability is a major limiting factor in plant productivity and plays a key role in plant species distribution over a given area. New technologies, such as terahertz quantum cascade lasers (THz-QCLs) have proven to be non-invasive, effective, and accurate tools for measuring and monitoring leaf water content. This study explores the feasibility of using an advanced THz-QCL device for measuring the absolute leaf water content in L.

An insight into the intermolecular vibrational modes of dicationic ionic liquids through far-infrared spectroscopy and DFT calculations.

Dicationic ionic liquids (DILs) are a subclass of the ionic liquid (IL) family and are characterized by two cationic head groups linked by means of a spacer. While DILs are increasingly attracting interest due to their peculiar physico-chemical properties, there is still a lack of understanding of their intermolecular interactions. Herein, we report our investigations on the intermolecular vibrational modes of two bromide DILs and of a bistriflimide DIL.

A straightforward multiparametric quality control protocol for proton magnetic resonance spectroscopy: Validation and comparison of various 1.5 T and 3 T clinical scanner systems.

Purpose: The aim of this study was to propose and validate across various clinical scanner systems a straightforward multiparametric quality assurance procedure for proton magnetic resonance spectroscopy (MRS).

Methods: Eighteen clinical 1.5 T and 3 T scanner systems for MRS, from 16 centres and 3 different manufacturers, were enrolled in the study.

Non-invasive absolute measurement of leaf water content using terahertz quantum cascade lasers.

Background: Plant water resource management is one of the main future challenges to fight recent climatic changes. The knowledge of the plant water content could be indispensable for water saving strategies. Terahertz spectroscopic techniques are particularly promising as a non-invasive tool for measuring leaf water content, thanks to the high predominance of the water contribution to the total leaf absorption.

STEAM-MiTiS: An MR spectroscopy method for the detection of scalar-coupled metabolites and its application to glutamate at 7 T.

Purpose: We herein present a spectroscopic technique for the detection of scalar-coupled metabolites based on stimulated echo acquisition mode (STEAM). The method is based on the time evolution of scalar-coupled metabolites at different mixing times and a constant echo time. The technique is optimized for targeting the metabolite glutamate at 7T.

Measurement of the optical parameters of the Virgo interferometer.

The Virgo interferometer, aimed at detecting gravitational waves, is now in a commissioning phase. Measurements of its optical properties are needed for the understanding of the instrument. We present the techniques developed for the measurement of the optical parameters of Virgo.

Single-frequency diode-pumped Yb:KYF(4) laser around 1030 nm.

Widely-tunable cw laser action has been demonstrated in a diode-pumped Yb:KYF(4) crystal. A comprehensive characterization of the active material and laser performance are reported, with particular attention to single-frequency laser operation. Single longitudinal-mode operation is achieved in the tuning range from 1020 to 1045 nm with a maximum output power of 150 mW.

Room-temperature diode-pumped Yb:KYF(4) laser.

Continuous-wave laser action has been demonstrated in a diode-pumped Yb:KYF(4) crystal. Crystal growth, spectroscopic measurements, and laser results are presented. A maximum output power of 505 mW, a slope efficiency of 43%, and a continuous wavelength tunability range of 65nm, from 1013 to 1078 nm, have been obtained at room temperature.

Room-temperature Q-switched Tm:BaY(2)F(8) laser pumped by CW diode laser.

We report on the realization of CW diode-pumped Tm:BaY(2)F(8) Q-switched laser at 1.93 microm. Active Q-switching was obtained by means of an intracavity Pockels cell.

Spectroscopy of Tm and Ho in KYF(4) single crystals.

We report on the spectroscopic characterization of Tm :KYF(4) and Ho :KYF(4) single crystals. The energy level splittings are given, as well as the Judd-Ofelt parameters, the polarized absorption and emission cross sections and the energy transfer coefficients. This allows to have a deeper understanding of the Tm-Ho-codoped KYF(4) system and shows KYF(4) to be a promising material for widely tunable and efficient 2 µm laser operation.

Effect of Cerium codoping on Er:BaY(2)F(8) crystals.

We present the Erbium (4)I(11/2) and (4)I(13/2) complete polarized spectroscopic investigation on a series of Er(3+),Ce(3+):BaY(2)F(8) single crystals as a function of Cerium concentration. The main results of room temperature lifetime investigation show that the (4)I(13/2) lifetime reduces from 15.6 ms to 10 ms, the (4)I(11/2) lifetime reduces from 8.

Widely tunable 1.94-microm Tm:BaY2F8 laser.

A novel BaY2F8 crystal doped with thulium ions is grown and extensively investigated. Owing to the large number of vibronic levels and to a favorable electron-phonon coupling, extremely wide absorption and emission bands around 1.9 microm are observed.

1-mJ Q-switched diode-pumped Nd:BaY(2)F(8) laser.

We report what is to our knowledge the first high repetition rate Q-switched Nd:BaY(2)F(8) (Nd:BaYF) laser pumped with a multiwatt fiber-coupled diode array tuned at 806 nm. As much as 2.42 W of average power and up to 1.