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The effect of BaF2, MgF2, and AlF3 on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]4 and [GeO]6 units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF2. The 27Al MAS NMR spectrum of BGG glass with AlF3 suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the 4I13/2→4I15/2 transition of Er3+ ions increases in the BGG + MgF2 glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties.

The ELI-NP facility, currently being built in Bucharest, Romania, will deliver an intense and almost monochromatic γ beam with tunable energy between 0.2 MeV and 19.5 MeV in two different beamlines. An articulated beam characterization system will be installed downstream of the collimator of each line. The system will use, as calibration candles, a few selected nuclear levels whose fluorescence condition will be monitored by a Nuclear Resonance Scattering System (NRSS). The NRSS will use a peculiar double-readout approach in order to detect resonant events overwhelming background: both scintillation and Cherenkov photons produced inside the same crystals will be separately read.

In this contribution we present the first example of a microfiuidic chip based on BaF2 for Infrared Microspectroscopy (IBMS) of living cells. The advantage in using barium fluoride as platform relies on its high IR transparency, especially in the spectral region below 1300 cm(-1), where the absorption bands of nucleic acids and carbohydrates are located. Barium fluoride is slightly soluble in water (0.12 g/100 g water) and it is potentially harmful for living cells. To overcome these problems, here we exploit an approach whose feasibility has been demonstrated previously on CaF2: the surface modification obtained by sputtering a thin Si layer on the surface. The Surface Modified Microfluidic Devices (SM-MD) hence obtained not only solve the BaF2 drawbacks, but also provide a silicon-like substrate fully compatible with standard micro-fabrication processes. These potentialities are here further explored in the direction of chemical or topographical nano-patterning of the silicon-like surface. The silicon thin layer was structured in the shape of 300 nm wide grooves (500 nm pitch) with a thickness of 35 nm by using standard NIL and etching processes; chemical patterning was achieved by exploiting silane chemistry. Finally, we tested the performances of these devices at SISSI beamline@Elettra, collecting IR spectra of single MDA-MB-231 living cells maintained either in physiological solution or complete medium. A comparison of the spectra of a single cell obtained in BaF2 and CaF2 MDs is reported. (C) 2013 Elsevier B.V. All rights reserved.

A highly compact and fast VME based readout board for BaF/sub 2/ scintillation detectors has been designed, developed, and finally tested in an in-beam experiment. Adapted to the excellent properties of BaF/sub 2/, the unit allows to digitize time, energy, and pulse-shape information of four detector channels in parallel. The board is piggy-back plugged onto a motherboard containing a high-speed 12-bit ADC and the VME interface, commercially available in the customized version CAEN V874 A. Both combine to one single VME slot. A first measurement of the photon response of a TAPS subarray with energy tagged photons up to 2.6 GeV documents the full functionality and excellent performance.

The response of PbWO4 to high-energy protons has been investigated in two test experiments at the proton facilities Cosy and AGOR. The determined energy resolution below 360 MeV of sigma/E = 1.44%/E-gamma(1/2) + 1.97% is comparable to the known photon response. Measured spectra of inelastically scattered protons below 85 MeV are even compared to similar distributions obtained for BaF2- and CeF3-detectors. (C) 2002 Elsevier Science B.V. All rights reserved.

The ex situ process for fabricating Ba2YCu3O6.5 + x superconducting tapes from BaF2- based precursors involves a hydration/oxidation reaction at ≈730 °C to 750 °C generally written as: (2BaF2+Y+3Cu)(amorphous)+(2H2O+2.25O2)(g)→Ba2YCu3O6.5+x(s)+4HF(g). However, microscopic observations of partially processed films suggest the presence of a transient liquid phase during conversion. Alternatively, the conversion reaction can be rewritten as the sum of several intermediate steps, including the formation of a barium hydroxide liquid: (BaF2)(amorphous)+2H2O(g)→Ba(OH)2(liq)+2HF(g). To evaluate the possibility of a hydroxide liquid conversion step, thermodynamic calculations on the stability of Ba(OH)2(liq) have been completed from 500 °C to 900 °C at 0.1 MPa ptotal. Based on currently available data, the calculated phase diagrams suggest that a viable hydroxide reaction path exists in the higher part of this temperature range. The calculations indicate that Ba(OH)2(liq) may be stable at log pH2O (Pa) values from ≈4 to 5, provided log pHF (Pa) values can be maintained below 0 to −1. Limited experimental confirmation is provided by results of an experiment on BaF2(s) at 815 °C, 0.1 MPa pH2O, in which essentially all F at the surface was replaced by O. It is therefore possible that processing routes exist for producing Ba2YCu3O6.5 + x based on the presence of a Ba(OH)2 liquid, which might have an effect on conversion rates and texturing in the superconducting film.

We have conducted two-photon spectroscopy of core excitons in BaF2. Synchrotron radiation and laser light were used for 5p core-electron excitation and Auger-free luminescence was detected as the signal. Two-photon excitation enables access to f and p orbitals that cannot be reached by one-photon excitation of electrons in p orbitals. It has been found that the spin-orbit splittings of 4f and 6p states of the Ba ion in BaF2 are 0.7 +/- 0.1 and 1.4 +/- 0.1 eV, respectively.