Production and Properties of the Liquid Scintillators used in the Stereo Reactor Neutrino Experiment

The electron antineutrino spectrum in the Stereo reactor experiment (ILL Grenoble) is measured via the inverse beta decay signals in an organic liquid scintillator. The six target cells of the Stereo detector are filled with about 1800 litres of Gd-loaded liquid scintillator optimised for the requirements of the experiment. These target cells are surrounded by similar cells containing liquid scintillator without the Gd-loading. The development and characteristics of these scintillators are reported. In particular, the transparency, light production and pulse shape discrimination capabilities of the organic liquids are discussed.Comment: 10 pages, 4 figure

Effects of pore modification on the templating of guest molecules in a 2D honeycomb network

This work was supported by the UK Engineering Physical Sciences Research Council (EPRSC) and the EU.1,7-Diadamantanethioperylene-3,4:9,10-tetracarboxylic diimide, (Ad-S)(2)-PTCDI, adsorbed on Au (111) from solution was investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). (Ad-S)(2)-PTCDI forms a well-ordered monolayer whose structure is described by a (2 root 63 x root 19) R19.1 degrees chiral unit cell containing four molecules. Codeposition of (Ad-S)(2)-PTCDI with 1,3,5-triazine-2,4,6-triamine (melamine) yields a honeycomb network whose (7 root 3 x 7 root 3)R30 degrees unit cell is identical to the unsubstituted PTCDI/melamine analogue. The effect of the adamantyl thioether moieties on the adsorption of guest molecules is investigated using adamantane thiol and C-60. While the thioether units do not affect the packing of adamantane thiol molecules a pronounced influence is seen in the case of fullerene. Pore modification involving different combinations of enantiomers of (Ad-S)(2)-PTCDI give rise to distinctly different arrangements of C-60 molecules. The diversity of patterns is further increased by the presence of unsubstituted PTCDI molecules.PostprintPeer reviewe

Density functional theory study of Pd aggregation on a pyridine-terminated self-assembled monolayer

Authors thank the School of Chemistry and EaStCHEM for support. The Chinese Scholarship Council is gratefully acknowledged for a stipend for Z. Y.By using density functional theory calculations, the initial steps towards Pd metal cluster formation on a pyridine‐terminated self‐assembled monolayer (SAM) consisting of 3‐(4‐(pyridine‐4‐yl)phenyl)propane‐1‐thiol on an Au(1 1 1) surface are investigated. Theoretical modelling allows the investigation of structural details of the SAM surface and the metal/SAM interface at the atomic level, which is essential for elucidating the nature of Pd–SAM and Pd–Pd interactions at the liquid/solid interface and gaining insight into the mechanism of metal nucleation in the initial stage of electrodeposition. The structural flexibility of SAM molecules was studied first and the most stable conformation was identified, planar molecules in a herringbone packing, as the model for Pd adsorption. Two binding sites are found for Pd atoms on the pyridine end group of the SAM. The strong interaction between Pd atoms and pyridines illustrates the importance of SAM functionalisation in the metal nucleation process. Consistent with an energetic driving force of approximately −0.3 eV per Pd atom towards Pd aggregation suggested by static calculations, a spontaneous Pd dimerisation is observed in ab initio molecular dynamic studies of the system. Nudged elastic band calculations suggest a potential route with a low energy barrier of 0.10 eV for the Pd atom diffusion and then dimerisation on top of the SAM layer.Publisher PDFPeer reviewe

Coordination-controlled electrodeposition of palladium/copper thin films onto a pyridine-terminated self-assembled monolayer

Support by the Chinese Scholarship Council and the University of St Andrews for a stipend (Z. Y.) are gratefully acknowledged. Electron microscopy was carried out at the Electron Microscopy Facility, School of Chemistry, University of St Andrews and we acknowledge recent funding for the Facility from the EPSRC (EP/T019298/1, EP/L017008/1) and the EPSRC Strategic Resources Grant (EP/R023751/1).A scheme for the electrodeposition of ultrathin bimetallic layers on top of a self-assembled monolayer (SAM) is investigated which combines the deposition of one metal (Pd) coordinated to a functionalized SAM (3-(4-pyridine-4-yl-phenyl)-propane-1-thiol, PyP3) on Au/mica with another metal (Cu) from the bulk electrolyte. The coordination-controlled electrodeposition (CCED) is a four-phase process comprising (i) Pd2+ coordination to the terminal pyridine units of the SAM, (ii) reduction of Pd and nanoparticle formation, (iii) formation of an intermixed shell of Pd and Cu, and (iv) deposition of bulk Cu. Chronoamperometry reveals a fast nucleation phase where Pd nanoparticles form within a few milliseconds and seed the Cu deposition. The Pd-Cu core-shell nature of deposited nanoparticles is confirmed by transmission electron microscopy (TEM). Harnessing the selective coordination of Pd2+ to PyP3, a one-pot procedure is further developed using electrolytes containing both Pd2+ and Cu2+ ions. Thus simplifying complexation and reduction, continuous Pd/Cu films are obtained in a multistep process as verified by scanning tunneling microscopy (STM). With a percolation threshold below 3 nm, CCED, as a SAM-controlled deposition strategy, offers an avenue for generation of ultrathin films.Publisher PDFPeer reviewe

Sequential nested assembly at the liquid/solid interface

This work was supported in part by The Leverhulme Trust (grant no. RPG-2013-177). The synthetic chemistry team thanks the Swiss National Science Foundation (SNF, grant no. 200020-159730) for continuous and generous financial support. BK acknowledges EaStCHEM and the Funds for Women Graduates (FfWG) for postgraduate studentships.Studying the stepwise assembly of a four component hybrid structure on Au(111)/mica, the pores of a hydrogen bonded bimolecular network of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (melamine) were partitioned by three and four-armed molecules based on oligo([biphenyl]-4-ylethynyl)benzene, followed by the templated adsorption of either C60 fullerene or adamantane thiol molecules. The characterisation by ambient scanning tunneling microscopy (STM) reveals that the pore modifiers exhibit dynamics which pronouncedly depend on the molecular structure. The three-armed molecule 1,3,5-tris([1,1′-biphenyl]-4-ylethynyl)benzene (3BPEB) switches between two symmetry equivalent configurations on a time scale fast compared to the temporal resolution of the STM. Derivatisation of 3BPEB by hydroxyl groups substantially reduces the switching rate. For the four-armed molecule configurational changes are observed only occasionally. The observation of isolated fullerenes and small clusters of adamantane thiol molecules, which are arranged in a characteristic fashion, reveals the templating effect of the trimolecular supramolecular network. However, the fraction of compartments filled by guest molecules is significantly below one for both the thermodynamically controlled adsorption of C60 and the kinetically controlled adsorption of the thiol with the latter causing partial removal of the pore modifier. The experiments, on the one hand, demonstrate the feasibility of templating by nested assembly but, on the other hand, also pinpoint the requirement for the energy landscape to be tolerant to variations in the assembly process.PostprintPeer reviewe

In-situ scrutiny of the relationship between polymorphic phases and properties of self-assembled monolayers of a biphenyl based thiol

This work has been supported by the Spanish Government under projects MAT2013-47869-C4-1-P and MAT2016-77852-C2-1-R (AEI/FEDER, UE) and the Generalitat de Catalunya 2014 SGR501 The authors acknowledge the MINECO project MAT2015-68994-REDC and the “‘Severo Ochoa”’ Program for Centers of Excellence in R&D (SEV-2015-0496). M. Paradinas thanks the Spanish Government for financial support through BES-2008-003588 FPI and PTA2014-09788-I fellowships. C. Munuera acknowledges financial support from the “Ramón y Cajal” program RYC-2014-16626.Two polymorphic phases of ω-(4′-methylbiphenyl-4-yl) butane-1-thiol (BP4) molecules formed on Au(111) were investigated by multidimensional atomic force microscopy, combining conductivity measurements, electrostatic characterization, friction force mapping, and normal force spectroscopy. Based on the same molecular structure but differing in molecular order, packing density, and molecular tilt, the two phases serve as a test bench to establish the structure–property relationships in self-assembled monolayers (SAMs). From a detailed analysis of the charge transport and electrostatics, the contributions of geometrical and electronic effects to the tunneling are discussed.PostprintPeer reviewe

Ivan Lupić i Bojana Schubert: Prvi hrvatski Shakespeare, Pučko otvoreno učilište »Dragutin Novak«, Ludbreg, 2016., 111 str.

The work was supported by EPSRC (EP/E061303/1 and EP/L017008/1). ADF acknowledges support from EPSRC (EP/I004602/1).The electrochemical deposition of Au onto Au substrates modified by self-assembled monolayers (SAMs) was studied by linear sweep voltammetry (LSV), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Patterned SAMs exhibiting electrochemical contrast were prepared by two different methods. One used microcontact printing (μCP) to generate a binary SAM of ω-(4'-methyl-biphenyl-4-yl)-propane thiol (CH3-C6H4-C6H4-(CH2)3-SH, MBP3) and octadecane thiol (CH3(CH2)17SH, ODT). Templated by the SAM, a gold microelectrode structure was electrodeposited featuring a line 15 μm wide and 3 mm long. After transfer to an epoxy substrate the structure proved to be electrically conductive across the full length. The other patterning method applied electron beam lithography (EBL) where electrochemical contrast was achieved by crosslinking molecules in a single component SAM of MBP3. An electron dose above 250 mC/cm2 results in a high deposition contrast. The choice of parameters for the deposition/lift-off process is found to be more critical for Au compared to Cu studied previously. The origin of the differences and implications for nanoscale patterning are discussed.PostprintPeer reviewe

Porous honeycomb self-assembled monolayers : tripodal adsorption and hidden chirality of carboxylate anchored triptycenes on Ag

S.D. and M.Z thank the Helmholtz Zentrum Berlin for the allocation of synchrotron radiation beamtime at BESSY II and financial support. The work was financially supported by the German Research Foundation (Deutsche Forschungsgemeinschaft; DFG) via grant ZH 63/39-1 (S.D. and M.Z.), EPSRC (doctoral training grant, R.O.d.l.M.), and CREST (Japan Science and Technology Agency; JST) via grant JPMJCR18I4 (T.F.) and also supported in part by “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” from MEXT, Japan. The authors acknowledge financial support through the Austrian Science Fund (FWF): P28051-N36.Molecules with tripodal anchoring to substrates represent a versatile platform for the fabrication of robust self-assembled monolayers (SAMs), complementing the conventional monopodal approach. In this context, we studied the adsorption of 1,8,13-tricarboxytriptycene (Trip-CA) on Ag(111), mimicked by a bilayer of silver atoms underpotentially deposited on Au. While tripodal SAMs frequently suffer from poor structural quality and inhomogeneous bonding configurations, the triptycene scaffold featuring three carboxylic acid anchoring groups yields highly crystalline SAM structures. A pronounced polymorphism is observed, with the formation of distinctly different structures depending on preparation conditions. Besides hexagonal molecular arrangements, the occurrence of a honeycomb structure is particularly intriguing as such an open structure is unusual for SAMs consisting of upright-standing molecules. Advanced spectroscopic tools reveal an equivalent bonding of all carboxylic acid anchoring groups. Notably, density functional theory calculations predict a chiral arrangement of the molecules in the honeycomb network, which, surprisingly, is not apparent in experimental scanning tunneling microscopy (STM) images. This seeming discrepancy between theory and experiment can be resolved by considering the details of the actual electronic structure of the adsorbate layer. The presented results represent an exemplary showcase for the intricacy of interpreting STM images of complex molecular films. They are also further evidence for the potential of triptycenes as basic building blocks for generating well-defined layers with unusual structural motifs.Publisher PDFPeer reviewe

Shape controlled assembly of carboxylic acids : formation of a binary monolayer by intercalation into molecular nanotunnels

Support by the Leverhulme Trust (RGP -2013-177) and EPSRC via doctoral training grants (R .O .d.l.M .,H.A.) and the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT) (PhD studentship to K.T.) is gratefully acknowledged. A. A. acknowledges the financial support by the DAAD-Aceh Scholarship of Excellence.Binary self-assembled monolayers (SAMs) combining a Y-shaped aromatic carboxylic acid (1,3,5-benzenetribenzoic acid, H3BTB) and a cage-type alicyclic carboxylic acid (adamantane carboxylic acid, AdCA) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The SAMs, prepared by molecular adsorption from solution on Au substrates modified by underpotential deposition of Ag, exhibit a pronounced dependence of their structure on the assembly protocol. Exposing an H3BTB SAM to AdCA, the highly regular row structure of the native H3BTB layer persists and STM imaging does not show signs of AdCA adsorption. This is in striking contrast to the disordered arrangements of H3BTB and the presence of AdCA employing the inverted adsorption sequence or coadsorption of the two molecules. However, spectroscopic analysis of the H3BTB SAM exposed to AdCA reveals the presence also of the latter, suggesting that the AdCA molecules are hidden in the nanotunnels of the H3BTB monolayer. Direct evidence for the intercalation of AdCA is obtained by STM manipulation experiments which lay bare areas of AdCA molecules upon local removal of H3BTB. Surprisingly, these are densely packed and arranged into a highly ordered monolayer. Formation of such a compact AdCA layer is explained by expulsion of AdCA from the H3BTB nanotunnels of the surrounding intact mixed SAM, driven by release of stress in the nanotunnels built up when AdCA is intercalated.PostprintPeer reviewe

Self-assembly of 1,3,5-benzenetribenzoic acid on Ag and Cu at the liquid/solid interface

Support by the Leverhulme Trust (RGP-2013-177) and EPSRC via a doctoral training grant (H.A.) is gratefully acknowledged.Assembly of 1,3,5-benzenetribenzoic acid (H3BTB) from solution on Au substrates modified by underpotential deposited Ag and Cu layers was studied by near edge X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy and scanning tunneling microscopy. Adsorption of H3BTB on Cu resulted in disordered layers with sporadic occurrence of ordered molecular aggregates. In contrast, highly ordered layers were obtained on Ag which exhibit a pronounced row structure and involve a monopodal bidentate adsorption geometry of the molecules through carboxylate coordinating bonding. The row structure arises from π-stacking of the molecules and is accompanied by hydrogen bonding interactions between the COOH groups of adjacent rows. As a consequence of the geometry of the H3BTB molecule and the dominance of intermolecular over molecule-substrate interactions, the SAM forms an open structure featuring a grooved surface and nanotunnels.PostprintPeer reviewe