Angularly resolved characterization of ion beams from laser-ultrathin foil interactions

Methods and techniques used to capture and analyze beam profiles produced from the interaction of intense, ultrashort laser pulses and ultrathin foil targets using stacks of Radiochromic Film (RCF) and Columbia Resin #39 (CR-39) are presented. The identification of structure in the beam is particularly important in this regime, as it may be indicative of the dominance of specific acceleration mechanisms. Additionally, RCF can be used to deconvolve proton spectra with coarse energy resolution while mantaining angular information across the whole beam

Luminescent Metal-organic frameworks for sensing of pollutants

contamination of soils, water and air by heavy metals, pesticides, gases, dioxins etc. pose a severe treat to environment and human health and affect the future generations. For these reasons, researchers around the world are currently working on developing new materials and technologies to preserve nature and offer a better future for the next generations. Metal-organic frameworks (MOFs) are materials that could help in this challenge thanks to their outstanding properties, extreme flexibility and relative ease of synthesis. In recent years, MOFs are showing that they are not only extremely porous materials and excellent catalysts, but some of them have also interesting optical properties making them good candidates for LEDs and luminescent sensors.[1] In particular, using luminescent MOFs (LMOFs) as sensors for qualitative and quantitative detection of pollutants has notable advantages: the crystalline structure of the MOFs is capable to select and concentrate the analyte and exclude potential interfering species enhancing considerably the sensitivity. Moreover, it is possible to design sensors that could be reused by recovering the MOFs.[2] Two main interaction and transduction mechanisms are possible in luminescent MOFs while used as sensor: on one hand a change in luminescent intensity (quenching or enhancement); on the other hand a change in the position of the emission band.[3] To develop sensors based on LMOFs are possible two different approaches: synthesize intrinsically luminescent MOFs or loading luminescent species (Dyes, QDs etc.) inside the MOFs by exploiting their porosity. In this study, we have synthesized two LMOFs, each one example of these two different approaches presented before and tested as sensors for heavy metal ions in water solutions: the intrinsically luminescent AgBDC and Zr-MOF-808 loaded with luminescent gold clusters Au25@BSA (Au25@MOF-808). AgBDC was synthesized from AgNO3 and terephthalic acid and characterized by XRD and FTIR, and then tested as luminescent sensor for heavy metals ions in water solutions. Our results show that Mn2+ and Hg2+ ions in μM concentrations are capable to quench the luminescence of AgBDC, making this MOFs a promising candidate as luminescent chemosensor for these two metal ions. Meanwhile Au25BSA@MOF-808 was obtained by loading into Zr-MOF-808 luminescent gold clusters Au25@BSA. It was structurally characterized by XRD, FTIR and N2 gas adsorption and later tested as sensor for heavy metals in water. Brillant results were obtained showing how this LMOF acts as highly sensitive sensor for Hg2+ ions in trace concentrations (nM) with very high selectivity, respect to many common metal ions in water solutions. Moreover, the Zr-MOF-808 structure is capable to shield the Au25 clusters from organic pollutants, increasing their selectivity and improves their thermal and temporal stability. Our result shows that AgBDC and Au25@MOF-808 could be used as sensors for heavy metal ions with excellent sensitivity and selectivity. More specifically Au25@MOF-808 is capable to detect Hg2+ in trace concentrations just by simple fluorescence measurements. In addition, these two LMOFs open the way to developments of solid-state sensors based on them for example: coatings, films, polymer matrix membrane which could be easily recovered and reused. These results have strong impact in sensoristics demonstrating that LMOFs can be valid candidates to design efficient, sensitive and selective sensors for pollutants helping us in the continuous environmental monitoring

Investigation on the luminescence properties of bare and Rhodamine B functionalized Zr-MOF-808

Metal organic frameworks (MOFs) are materials well known for their high surface and catalytic properties as well as because they are relatively easy to synthesize and, in some cases, extremely f lexible.[1] Recently, there has been also a growing interest in the optical properties of these materials, particularly in luminescence, which has potential applications in various fields, such as sensors, LEDs, scintillators, and bioimaging agents....

In situ single-crystal x-ray diffraction studies of an anomalous nitric oxide adsorption in a partially activated metal–organic framework

Funding: The authors gratefully acknowledge the assistance of Diamond Light Source for access to beamline I19-2 under proposals CY32865-1 and CY35900. The authors are also grateful for financial assistance from the ERC under advanced grant 787073, the EPSRC (EP/X014436/1 and EP/V008498/1), and the Slovenian Research and Innovation agency (Research programs P1-0021).Metal–organic frameworks (MOFs), with their high porosities and surface areas, show great utility in the field of gas adsorption. To unlock this porosity, MOFs are generally fully activated by removing all adsorbed guests using high temperatures and low pressures. However, this is energy intensive and can be unfeasible if the MOF is part of a composite, where the maximum temperature of the composite is below the activation temperature. To investigate the effect of activation temperature on adsorption, a series of in situ single-crystal X-ray diffraction (scXRD) studies were performed on Ni-MOF-74 loaded with the gas nitric oxide (NO) under different conditions. These experiments uncovered anomalous adsorption results where partially activated samples adsorb ∼14% more NO per framework material than did the fully activated sample. The scXRD experiments revealed a new NO binding site that is only present if the open metal sites are partially occupied by water molecules. To shed more light on the respective binding of the two different NO sites in Ni-MOF-74, these were studied in situ under different treatment conditions, such as the exposure to vacuum at different temperatures. This study yields insights into the nature of binding sites in MOFs, how these are affected by activation, and helps to pave the way for the improved design of processing conditions.Peer reviewe

Origin of the solid-state luminescence of MIL-53(Al) and its connection to the local crystalline structure

Metal-organic frameworks (MOFs) are extensively studied due to their unique surface properties, enabling many intriguing applications. Breathing MOFs, a subclass of MOFs, have gained recent interest for their ability to undergo structural changes based on factors like temperature, pressure, adsorbed molecules. Certain MOFs also exhibit remarkable optical properties useful for applications such as sensors, light-emitting diodes, and scintillators. The most promising MOFs possess high porosity, breathing properties, and photoluminescence activities, allowing for improved device responsiveness and selectivity. Understanding the relationship between crystal structures and photoluminescence properties is crucial in these cases. As studies on this topic are still very limited, we report for the first time an exhaustive study on the solid-state luminescence of the breathing MOF MIL-53(Al), that can stabilize in three different crystalline structures: open-pore, hydrated narrow-pore and closed-pore. We unveil a fascinating solid-state luminescence spectrum, comprising three partially overlapping bands, and elucidate the intricate electronic transitions within each band as well as their intimate correlation with the local crystalline structures. Our characterizations of spectroscopic properties and decay times provide a deeper understanding of the luminescent behaviour of MIL-53(Al) and demonstrate that is possible to identify present crystalline structures by optical measurements or to modify the optical properties inducing structural transitions for this type of materials. These insights could help to design next-generation, selective sensors or smart light emitting devices

In situ single-crystal X-ray diffraction studies of physisorption and chemisorption of SO2 within a metal-organic framework and its competitive adsorption with water

Funding: The authors are also grateful for financial assistancefrom the ERC under advanced grant 787073, the EPSRC for a studentship (EP/N509759/1) and support via the Collaborative Computational Projecton NMR Crystallography CCP-NC (EP/T02662/1), and the CRITICAT Centre for Doctoral Training (EP/L016419/1).Living on an increasingly polluted planet, the removal of toxic pollutants such as sulfur dioxide (SO2) from the troposphere and power station flue gas is becoming more and more important. The CPO-27/MOF-74 family of metal–organic frameworks (MOFs) with their high densities of open metal sites is well suited for the selective adsorption of gases that, like SO2, bind well to metals and have been extensively researched both practically and through computer simulations. However, until now, focus has centered upon the binding of SO2 to the open metal sites in this MOF (called chemisorption, where the adsorbent–adsorbate interaction is through a chemical bond). The possibility of physisorption (where the adsorbent–adsorbate interaction is only through weak intermolecular forces) has not been identified experimentally. This work presents an in situ single-crystal X-ray diffraction (scXRD) study that identifies discrete adsorption sites within Ni-MOF-74/Ni-CPO-27, where SO2 is both chemisorbed and physisorbed while also probing competitive adsorption of SO2 of these sites when water is present. Further features of this site have been confirmed by variable SO2 pressure scXRD studies, DFT calculations, and IR studies.Publisher PDFPeer reviewe

The laser-hybrid accelerator for radiobiological applications

The `Laser-hybrid Accelerator for Radiobiological Applications', LhARA, is conceived as a novel, uniquely-flexible facility dedicated to the study of radiobiology. The technologies demonstrated in LhARA, which have wide application, will be developed to allow particle-beam therapy to be delivered in a completely new regime, combining a variety of ion species in a single treatment fraction and exploiting ultra-high dose rates. LhARA will be a hybrid accelerator system in which laser interactions drive the creation of a large flux of protons or light ions that are captured using a plasma (Gabor) lens and formed into a beam. The laser-driven source allows protons and ions to be captured at energies significantly above those that pertain in conventional facilities, thus evading the current space-charge limit on the instantaneous dose rate that can be delivered. The laser-hybrid approach, therefore, will allow the vast ``terra incognita'' of the radiobiology that determines the response of tissue to ionising radiation to be studied with protons and light ions using a wide variety of time structures, spectral distributions, and spatial configurations at instantaneous dose rates up to and significantly beyond the ultra-high dose-rate `FLASH' regime. It is proposed that LhARA be developed in two stages. In the first stage, a programme of in vitro radiobiology will be served with proton beams with energies between 10MeV and 15MeV. In stage two, the beam will be accelerated using a fixed-field accelerator (FFA). This will allow experiments to be carried out in vitro and in vivo with proton beam energies of up to 127MeV. In addition, ion beams with energies up to 33.4MeV per nucleon will be available for in vitro and in vivo experiments. This paper presents the conceptual design for LhARA and the R&D programme by which the LhARA consortium seeks to establish the facility