Quantum light from a whispering-gallery-mode disk resonator

Optical parametric down-conversion has proven to be a valuable source of nonclassical light. The process is inherently able to produce twin-beam correlations along with individual intensity squeezing of either parametric beam, when pumped far above threshold. Here, we present for the first time the direct observation of intensity squeezing of -1.2 dB of each of the individual parametric beams in parametric down-conversion by use of a high quality whispering-gallery-mode disk resonator. In addition, we observed twin-beam quantum correlations of -2.7 dB with this cavity. Such resonators feature strong optical confinement and offer tunable coupling to an external optical field. This work exemplifies the potential of crystalline whispering-gallery-mode resonators for the generation of quantum light. The simplicity of this device makes the application of quantum light in various fields highly feasible.     

Spectroscopy and electrochemical properties of a homologous series of acetylacetonato and hexafluoroacetylacetonato cyclopalladated and cycloplatinated complexes

A photophysical, electrochemical and computational study has been performed on a homologous series of cyclometallated Pd(ii) () and Pt(ii) () complexes of general formula [(C,N)M(O,O)]; (H(C,N) = azobenzene, 2-phenylpyridine, benzo[h]quinoline; M = Pd, Pt; H(O,O) = acetylacetone, hexafluoroacetylacetone). Experimental and computational data have shown the strong influence exerted by electronegativity of the ancillary ligand on the frontier orbitals of the complexes, such an effect being enhanced for the Pt(ii) species.     

SEM-EDS investigation on PM10 data collected in Central Italy: Principal Component Analysis and Hierarchical Cluster Analysis

Background

Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied on PM10 particle data in order to: identify particle clusters that can be differentiated on the bases of their chemical composition and morphology, investigate the relationship among the chemical and morphological parameters and evaluate differences among the sampling sites. PM10 was collected in 3 different sites in central Italy characterized by different conditions: yard, urban and rural sites. The concentration of 20 chemical parameters (C, O, Na, Mg, Al, Si, P, Cd, Cl, K, Ca, Sn, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn) were determined by Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy (SEM-EDS) and the particle images were processed by an image analysis software in order to measure: Area, Aspect Ratio, Roundness, Fractal Dimension, Box Width, Box Height and Perimeter.

Result

Results revealed the presence of different clusters of particles, differentiated on the bases of chemical composition and morphological parameters (aluminosilicates, calcium particles, biological particles, soot, cenosphere, sodium chloride, sulphates, metallic particles, iron spherical particles). Aluminosilicates and Calcium particles of rural and urban sites showed a similar nature due to a mainly natural origin, while those of the yard site showed a more heterogeneous composition mainly related to human activity. Biological particles and soot can be differentiated on the bases of the higher loads of Fractal Dimension, which characterizes soot, and content of Na, Mg, Ca, Cl and K which characterize the biological ones. The soot of the urban site showed higher loadings of Roundness and Fractal Dimension than the soot belonging to the yard and rural sites, this was due to the different life time of the particles. The metal particles, characterized mainly by the higher loading of iron, were present in two morphological forms: spherical and angular particles. The first were generated by a fusion process at high temperature, while the second one had crustal origin (those characterized by typical terrigenous elements) and also human origin.

Conclusion

In this work a protocol for the morphological-chemical characterization of single particles has been developed. SEM analysis allows to classify particles in 10 different families and PCA and HCA have provided information about the sources of PM and similarities and differences among the sites.

Open image in new window

     

Maximum-likelihood estimation of Mueller matrices

We show that the method of maximum-likelihood estimation, recently introduced in the context of quantum process tomography, can be applied to the determination of Mueller matrices characterizing the polarization properties of classical optical systems. Contrary to linear reconstruction algorithms, the proposed method yields physically acceptable Mueller matrices even in the presence of uncontrolled experimental errors. We illustrate our method with the case of an unphysical measured Mueller matrix taken from the literature.     

UV/Vis to NIR Photoconduction in Cyclopalladated Complexes

Funky discotics : Photoconductivity is measured in newly synthesized cyclopalladated metallomesogens exhibiting hexagonal columnar mesophases at room temperature. The tuning of the HOMO/LUMO energy levels by modification of the chain/core linkage (ester 1 vs ether 2 ) makes compound 2 photoconductive across the whole UV/Vis/NIR range.

     

Thermal analysis of zeolite ZSM-5 precursors with different Si/Al ratios

The thermal analysis of crystalline zeolite ZSM-5 precurcors with different Si/Al ratios was carried out in a nitrogen atmosphere. Different interactions between tetrapropylammonium species and the zeolitic environment were evidenced, depending on the Al content of the crystalline precursors. The results support the mechanism of ZSM-5 formation through a condensation process from the liquid phase.

---

Zusammenfassung Thermische Analysen kristalliner Zeolith- (ZSM-5) Vorprodukte mit unterschiedlichen Verhältnissen Si/Al wurden in Stickstoffatmosphäre ausgeführt. Verschiedene Wechselwirkungen zwischen den Tetrapropylammonium-Spezies und ihrer zeolithischen Umgebung wurden nachgewiesen, die vom Aluminiumgehalt der kristallinen Vorprodukte abhängen. Die Ergebnisse sprechen für einen Bildungsmechanismus des ZSM-5 über einen Kondensationsprozess aus der flüssigen Phase.

---

ZSM-5 . . ZSM-5 .

---

---

This work was carried out with the financial support of the Italian National Research Council Progetto Finalizzato Energetica 2.     

Adsorption of 2-methylbenzoic acid onto MCM-41 mesoporous material: kinetics and equilibrium studies

Ordered mesoporous molecular sieves are widely studied as alternative materials in areas where sorptive and catalytic applications are required. MCM-41 type mesoporous material was tested as sorbent of 2-methylbenzoic acid (MBA), an aromatic carboxylic acid selected as model molecule for adsorption studies on mesoporous silicas. Adsorption kinetic studies of MBA on MCM-41 type materials were carried out using ethanol solutions at different MBA concentrations. Experimental results followed Langmuir isotherm model showing large adsorption capacity (3.5?g/g). Two kinetic models, the pseudo first- and second-order, were selected to describe the adsorption process and to determine the best model fitting with the experimental data. Kinetic parameters for each kinetic equation were calculated and discussed. It was shown that the MBA adsorption process onto MCM-41 material could be described by the pseudo-second-order equation and that the MCM-41 performs as a suitable adsorbent material.     

Optimizing ammonia processing conditions to enhance susceptibility of legumes to fiber hydrolysis

A warm-season legume, Florigraze rhizoma peanut (FRP), was used as the source of fiber to produce sugars. FRP was subjected to several ammonia-processing conditions using temperature, biomass moisture content, and ammonia loading as process variables during a 5-min treatment. A cellulase loading of 2 FPU/g DM and 24 h incubation were used to produce the sugars. Total sugar yield was 3.34-fold higher in the optimal treatment (1.5 g ammonia/g DM-60%-90°C) compared to untreated and was 65.3% of theoretical. Cellulose and hemicellulose conversions increased from 30 and 15.5% in untreated FRP to 78 and 34% in treated FRP.