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Molecular doping can increase the conductivity of organic semiconductors and plays an increasingly important role in emerging and established plastic electronics applications. 4-(1,3-Dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)-N,N-dimethylaniline (N-DMBI-H) and tris(pentafluorophenyl)borane (BCF) are established n- and p-dopants, respectively, but neither functions as a simple one-electron redox agent. Molecular hydrogen has been suggested to be a byproduct in several proposed mechanisms for doping using both N-DMBI-H and BCF. In this paper we show for the first time the direct detection of molecular hydrogen in the uncatalysed doping of a variety of polymeric and molecular semiconductors using these dopants. Our results provide insight into the doping mechanism, providing information complementary to that obtained from more commonly applied methods such as optical, electron spin resonance, and electrical measurements.

Angle resolved XRF (AR-XRF) is an analytical technique in which the sample is analyzed at different angles of detection or irradiation. The change in the geometry affects the intensity of the elemental characteristic emission from the sample, which depends on the in-depth distribution of analyte. In this paper, for the first time, we apply AR-XRF to gilding samples that mime real cultural heritage ones. The samples analysed, also investigated with scanning electron microscopy, present small lateral inhomogeneities and a rough surface. Moreover, we illustrate how to analyze AR-XRF data, from the collection of XRF spectra to the creation of AR-XRF profiles and the fitting of data using Sherman's equation. Using AR-XRF combined with the fundamental parameters method we calculate the massive thickness of laboratory made layered samples.

In this paper, we address the unique nature of fully textured, high surface-to-volume 3C-SiC films, as produced by intrinsic growth anisotropy, in turn generated by the high velocity of the stacking fault growth front in two-dimensional (111) platelets. Structural interpretation of high resolution scanning electron microscopy and transmission electron microscopy data is carried out for samples grown in a hot-wall low-pressure chemical vapour deposition reactor with trichlorosilane and ethylene precursors, under suitable deposition conditions. By correlating the morphology and the X-ray diffraction analysis we also point out that twinning along (111) planes is very frequent in such materials, which changes the free-platelet configuration.

The development of hybrid nanoscintillators is hunted for the implementation of modern detection technologies, like in high energy physics, homeland security, radioactive gas sensing, and medical imaging, as well as of the established therapies in radiation oncology, such as in X-ray activated photodynamic therapy. Engineering of the physico-chemical properties of nanoparticles (NPs) enables the manufacture of hybrids in which the conjugation of inorganic/organic components leads to increased multifunctionality and performance. However, the optimization of the properties of nanoparticles in combination with the use of ionizing radiation is not trivial: a complete knowledge on the structure, composition, physico-chemical features, and scintillation property relationships in hybrid nanomaterials is pivotal for any applications exploiting X-rays. In this paper, the design of hybrid nanoscintillators based on ZnO grown onto porous SiO2 substrates (ZnO/SiO2) has been performed in the view to create nanosystems potentially suitable in X-ray activated photodynamic therapy. Indeed, cytotoxic porphyrin dyes with increasing concentrations have been anchored on ZnO/SiO2 nanoparticles through amino-silane moieties. Chemical and structural analyses correlated with photoluminescence reveal that radiative energy transfer between ZnO and porphyrins is the principal mechanism prompting the excitation of photosensitizers. The use of soft X-ray excitation results in a further sensitization of the porphyrin emission, due to augmented energy deposition promoted by ZnO in the surroundings of the chemically bound porphyrin. This finding unveils the cruciality of the design of hybrid nanoparticles in ruling the efficacy of the interaction between ionizing radiation and inorganic/organic moieties, and thus of the final nanomaterial performances towards the foreseen application.

Luminescent solar concentrators (LSCs) are becoming an increasingly relevant topic for building integrated photovoltaics. Even if such devices are relatively simple planar waveguides doped with a luminescent material, the achievement of relevant efficiencies requires a careful optimisation of both the matrix and the luminophore. Most of the recent literature focuses on the performance, yet the overall sustainability of the strategy is a topic at least as important. In this respect the luminophore plays a crucial role. Suitable materials must feature a near unit emission quantum yield, efficient light harvesting and a large separation between absorption and emission to reduce reabsorption losses. Due to the target application, such materials must also be readily available in large quantities through sustainable processes. Instead of going for performance first and then scaling up/optimising the synthesis, in this paper we offer a reversed perspective. We have first designed and computationally characterised materials having structural features compatible with a green chemistry synthetic approach, namely, micellar catalysis. Later, we have characterised the most promising materials in LSC devices, and we have compared their performance with commercially available, non-green chemistry compliant alternatives having similar spectral features. In the overall, we demonstrate comparable performance, but greatly improved sustainability and scalability. This journal is

In this paper we introduce the use of molecular metal clusters as precursors for the in situ formation of nanoparticles with a high activity and surprising stability as electrocatalysts in energy conversion. The work is relevant in the present quest for remediation of greenhouse gas production and global warming, where fuel cells and metal and lithium air batteries are intended to play a crucial role. The research for an increased efficiency of these devices needs to solve the problems linked to the Oxygen Reduction Reaction (ORR), which plays a key role in these processes, due to its sluggish electrochemical kinetics that must be increased by a suitable electrocatalyst. Here we describe the facile synthesis of a new cathode material for fuel cells based on CO–Pt molecular clusters that are strongly bound to Vulcan XC72Rs. The Pt–CO bond can be removed just after the synthesis, by thermal treatment at 450 K, or once in solution, leaving low-coordinated, highly reactive surface Pt atoms. The materials are investigated thoroughly using identical-location transmission electron microscopy, X-ray diffraction (with pair distribution function) and X-ray absorption measurements, revealing an extremely small, yet controlled, particle size (1–2 nm), with high structural and morphological stability, and lack of any aggregation process after thermal treatment. The surprising stability is related to the quite large number of Pt–C bonds that the nanoparticles form with the support, allowing them to attach stably onto the carbonaceous moiety. At the same time, the nanoparticles are particularly strained, and enclose a high defect density, thus enhancing their catalytic properties. The best performing composite presents a mass activity of 225 mA mgPt @ 0.9 V vs. RHE for the ORR, and a less cathodic onset potential compared with a conventional Pt nanoparticle cathode, used as a benchmark under the same experimental conditions, while in turn having a lower noble metal content.

In the last few years, several monitoring programs were established as an effect of the EU Directives which included requirements for monitoring the quality of water resources (drinking water, groundwater and surface water). Plant Protection Products (PPPs) are an obvious target for monitoring activities, since they are directly released into the environment. In Italy, the National Environmental Protection Agency (ISPRA) has recently published several reports containing the results of the National Plans for Control of Environmental Effects of PPPs. These documents contain the collection of monitoring data related to the presence of PPP residues in surface and groundwater systems. In this paper, these results (monitoring campaigns from 2005 to 2009) were analysed. Particularly, the attention was focused on the concentration levels of terbuthylazine (TBZ) and its metabolite desethyl-terbuthylazine (DTZ) detected in the groundwater systems of the Lombardia Region (Northern Italy). The analysis allowed us to identify the spatial and temporal trends of contamination of both substances. Furthermore the DTZ/TBZ ratio was calculated in order to recognize point and non-point sources of contamination

Latex gloves are employed by felons who want to avoid shedding fingermarks or biological traces, and are sometimes discarded on the crime scene or nearby. Comparison between the gloves found at the crime scene and those seized in the suspect's premises can provide useful information to investigators. This paper proposes the use of 1H time domain nuclear magnetic resonance (TD-NMR) as a method for performing such a comparison. Two parameters can be quantified by this technique: the proton weight fraction, which is correlated to the chemical nature and formulation of the material, and the relaxation time T2, which is a measure of polymer chain dynamics. Both these features can be ultimately associated to differences in raw materials, formulation and processing of the gloves, thereby offering a means to discriminate items which are indistinguishable by visual examination. TD-NMR, without sample preparation and preserving the integrity of the specimen, allows differentiating 88% of the possible pairs of samples in a population of 20 latex gloves. TD-NMR data are complementary to those coming from thermal analysis. © The Royal Society of Chemistry 2011.