Observing thermal lensing with quantum light

The introduction of quantum methods in spectroscopy can provide enhanced performance and technical advantages in the management of noise. We investigate the application of quantum illumination in a pump and probe experiment. Thermal lensing in a suspension of gold nanorods is explored using a classical beam as the pump and the emission from parametric downconversion as the probe. We obtain an insightful description of the behaviour of the suspension under pumping with a method known to provide good noise rejection. Our findings are a further step towards investigating effects of quantum light in complex plasmonic media

Oxidized Palladium Supported on Ceria Nanorods for Catalytic Aerobic Oxidation of Benzyl Alcohol to Benzaldehyde in Protic Solvents

In the present study, the catalytic activity of palladium oxide (PdOx) supported on ceria nanorods (CeO2-NR) for aerobic selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) was evaluated. The CeO2-NR was synthesized hydrothermally and the Pd(NO3)2 was deposited by a wet impregnation method, followed by calcination to acquire PdOx/CeO2-NR. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). In addition, the TPR-reduced PdOx/CeO2-NR (PdOx/CeO2-NR-Red) was studied by XRD, BET, and XPS. Characterizations showed the formation of CeO2-NR with (111) exposed plane and relatively high BET surface area. PdOx (x > 1) was detected to be the major oxide species on the PdOx/CeO2-NR. The activities of the catalysts in BnOH oxidation were evaluated using air, as an environmentally friendly oxidant, and various solvents. Effects of temperature and palladium oxidation state were investigated. The PdOx/CeO2-NR showed remarkable activity when protic solvents were utilized. The best result was achieved using PdOx/CeO2-NR and boiling ethanol as solvent, leading to 93% BnOH conversion and 96% selectivity toward PhCHO. A mechanistic hypothesis for BnOH oxidation with PdOx/CeO2-NR in ethanol is presente

Fast remote spectral discrimination through ghost spectrometry

Assessing the presence of chemical, biological, radiological and nuclear threats is a crucial task which is usually dealt with by analyzing the presence of spectral features in a measured absorption profile. The use of quantum light allows to perform these measurements remotely without compromising the measurement accuracy through ghost spectrometry. However, in order to have sufficient signal-to-noise ratio, it is typically required to wait long acquisition times, hence subtracting to the benefits provided by remote sensing. In many instances, though, reconstructing the full spectral lineshape of an object is not needed and the interest lies in discriminating whether a spectrally absorbing object may be present or not. Here we show that this task can be performed fast and accurately through ghost spectrometry by comparing the low resources measurement with a reference. We discuss the experimental results obtained with different samples and complement them with simulations to explore the most common scenarios

Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids

In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol,trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl4−/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NOxwith the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction

Study of the interaction mechanism between hydrophilic thiol capped gold nanoparticles and melamine in aqueous medium

In the last years, intense efforts have been made in order to obtain colloidal-based systems capable of pointing out the presence of melamine in food samples. In this work, we reported about the recognition of melamine in aqueous solution, using gold nanoparticles stabilized with 3-mercapto-1-propanesulfonate (AuNPs-3MPS), with the aim of deepening how the recognition process works. AuNPs were synthesized using a wet chemical reduction method. The synthesized AuNPs-3MPS probe was fully characterized, before and after the recognition process, by both physicochemical (UV–vis, FT-IR, 1H-NMR, DLS and ζ-potential) and morphostructural techniques (AFM, HR-TEM). The chemical and electronic structure was also investigated by SR-XPS. The sensing method is based on the melamine-induced aggregation of AuNPs; the presence of melamine was successfully detected in the range of 2.5−500 ppm. The results achieved also demonstrate that negatively charged AuNPs-3MPS are potentially useful for determining melamine contents in aqueous solution. SR-XPS measurements allowed to understand interaction mechanism between the probe and the analyte. The presence of sulfonate groups allows a mutual interaction mediated by electrostatic bonds between nanoparticles surface thiols and positively charged amino groups of melamine molecules