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Instruments / Technical Area	Publication Details	Published
I09-Surface and Interface Structural Analysis	The structure of VOPc on Cu(111): Does V=O point up, or down, or both? P. J. Blowey , R. J. Maurer , L. A. Rochford , D. A. Duncan , Jie Hun Kang , D. A. Warr , A. J. Ramadan , T.-l. Lee , P. K. Thakur , G. Costantini , K. Reuter , D. P. Woodruff The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.8b07530 Diamond Proposal Number(s): [9459, 14524, 15899] Show Abstract ▼ Abstract: The local structure of the non-planar phthalocyanine, vanadyl phthalocyanine (VOPc), adsorbed on Cu(111) at a coverage of approximately one half of a saturated molecular layer, has been investigated by a combination of normal-incidence X-ray standing waves (NIXSW), scanned-energy mode photoelectron diffraction (PhD) and density-functional theory (DFT), complemented by scanning tunnelling microscopy (STM). Qualitative assessment of the NIXSW data clearly shows that both ‘up’ and ‘down’ orientations of the molecule (with V=O pointing out of, and into, the surface) must coexist on the surface. O 1s PhD proves to be inconclusive regarding the molecular orientation. DFT calculations, using two different dispersion correction schemes, show good quantitative agreement with the NIXSW structural results for equal co-occupation of the two different molecular orientations and clearly favour the Many Body Dispersion (MBD) method to deal with long-range dispersion forces. The calculated relative adsorption energies of the differently-oriented molecules at the lowest coverage show a strong preference for the ‘up’ orientation, but at higher local coverages, this energetic difference decreases and mixed orientation phases are almost energetically equivalent to pure ‘up’ oriented phases. DFT-based Tersoff-Hamann simulations of STM topographs for the two orientations cast some light on the extent to which such images provide a reliable guide to molecular orientation.	Oct 2018
I09-Surface and Interface Structural Analysis	Re-evaluating how charge transfer modifies the conformation of adsorbed molecules P. J. Blowey , S. Velari , L. A. Rochford , Da. A. Duncan , D. A. Warr , T.-l. Lee , A. De Vita , G. Costantini , D. P. Woodruff Nanoscale 4 DOI: 10.1039/C8NR02237B Diamond Proposal Number(s): [8436] Open Access Show Abstract ▼ Abstract: The archetypal electron acceptor molecule, TCNQ, is generally believed to become bent into an inverted bowl shape upon adsorption on the coinage metal surfaces on which it becomes negatively charged. New quantitative experimental structural measurements show that this is not the case for TCNQ on Ag(111). DFT calculations show that the inclusion of dispersion force corrections reduces not only the molecule-substrate layer spacing but also the degree of predicted molecular bonding. However, complete agreement between experimentally-determined and theoretically-predicted structural parameters is only achieved with the inclusion of Ag adatoms into the molecular layer, which is also the energetically favoured configuration. The results highlight the need for both experimental and theoretical quantitative structural methods to reliably understand similar metal–organic interfaces and highlight the need to re-evaluate some previously-investigated systems.	Jul 2018
I09-Surface and Interface Structural Analysis	Direct measurement of Ni incorporation into Fe 3 O 4 (001) P. T. P. Ryan , Z. Jakub , J. Balajka , J. Hulva , M. Meier , J. T. Kuchle , P. J. Blowey , P. K. Thakur , C. Franchini , D. J. Payne , D. P. Woodruff , L. A. Rochford , F. Allegretti , T.-l. Lee , G. S. Parkinson , D. A. Duncan Physical Chemistry Chemical Physics 115 DOI: 10.1039/C8CP02516A Diamond Proposal Number(s): [16403, 18191, 13817] Open Access Show Abstract ▼ Abstract: The normal incidence X-ray standing wave (NIXSW) technique has been used to follow the evolution of the adsorption geometry of Ni adatoms on the Fe3O4(001)-(√2 × √2)R45° surface as a function of temperature. Two primary surface region sites are identified: a bulk-continuation tetrahedral site and a sub-surface octahedral site, the latter site being preferred at higher annealing temperatures. The ease of incorporation is linked to the presence of subsurface cation vacancies in the (√2 × √2)R45° reconstruction and is consistent with the preference for octahedral coordination observed in the spinel compound NiFe2O4.	Jun 2018
I09-Surface and Interface Structural Analysis	Probing the interplay between geometric and electronic structure in a two-dimensional K-TCNQ charge transfer network P. J. Blowey , Luke A. Rochford , David Duncan , Daniel Warr , T.-l. Lee , D. P. Woodruff , Giovanni Costantini Faraday Discuss. DOI: 10.1039/C7FD00093F Show Abstract ▼ Abstract: Scanning tunnelling microscopy (STM), low energy electron diffraction (LEED), ultraviolet and soft X-ray photoelectron spectroscopy (UPS and SXPS) have been used to characterise the formation of a coadsorption phase of TCNQ and K on Ag(111), while the normal incident X-ray standing waves (NIXSW) technique has been used to obtain quantitative structural information. STM and LEED show an ordered incommensurate phase is formed in which the K atoms are surrounded by four TCNQ molecules in a ‘windmill’ motif, characteristic of other metal/TCNQ phases, in which the nominal TCNQ:K stoichiometry is 1:1. UPS and SXPS data indicate the TCNQ is in a negatively-charged state. NIXSW results show that the carbon core of the TCNQ is essentially planar at a height above the Ag(111) surface closely similar to that found without coadsorbed K. In the presence of TCNQ the height of the K ions above the surface is significantly larger than on clean Ag(111), and the ions occupy sites above ‘holes’ in the TCNQ network. NIXSW data also show that the N atoms in the molecules must occupy sites with at least two different heights above the surface, which can be reconciled by a tilt or twist of the TCNQ molecules, broadly similar to the geometry that occurs in bulk TCNQ/K crystals.	Mar 2017
I09-Surface and Interface Structural Analysis	Direct quantitative identification of the “surface trans-effect” Peter Deimel , Reda M. Bababrik , Bin Wang , Philip Blowey , Luke Rochford , Pardeep K. Thakur , Tien-lin Lee , Marie-laure Bocquet , Johannes V. Barth , Phil Woodruff , David Duncan , Francesco Allegretti Chem. Sci. DOI: 10.1039/C6SC01677D Diamond Proposal Number(s): [8940] Open Access Show Abstract ▼ Abstract: The strong parallels between coordination chemistry and adsorption on metal surfaces, with molecules and ligands forming local bonds to individual atoms within a metal surface, have been established over many years of study. The recently proposed “surface trans-effect” (STE) appears to be a further manifestation of this analogous behaviour, but so far the true nature of the modified molecule–metal surface bonding has been unclear. The STE could play an important role in determining the reactivities of surface-supported metal–organic complexes, influencing the design of systems for future applications. However, the current understanding of this effect is incomplete and lacks reliable structural parameters with which to benchmark theoretical calculations. Using X-ray standing waves, we demonstrate that ligation of ammonia and water to iron phthalocyanine (FePc) on Ag(111) increases the adsorption height of the central Fe atom; dispersion corrected density functional theory calculations accurately model this structural effect. The calculated charge redistribution in the FePc/H2O electronic structure induced by adsorption shows an accumulation of charge along the σ-bonding direction between the surface, the Fe atom and the water molecule, similar to the redistribution caused by ammonia. This apparent σ-donor nature of the observed STE on Ag(111) is shown to involve bonding to the delocalised metal surface electrons rather than local bonding to one or more surface atoms, thus indicating that this is a true surface trans-effect.	Jun 2016
	Structural Templating in a Nonplanar Phthalocyanine Using Single Crystal Copper Iodide Luke Rochford , Alexandra Ramadan , Dean S. Keeble , Mary Ryan , Sandrine Heutz , Tim S. Jones Advanced Materials Interfaces 2, n/a - n/a DOI: 10.1002/admi.201400540 Open Access Show Abstract ▼ Abstract: Solution-grown copper iodide crystals are used as substrates for the templated growth of the nonplanar vanadyl phthalocyanine using organic molecular beam deposition. Structural characterization reveals a single molecular orientation produced by the (111) Miller plane of the copper iodide crystals. These fundamental measurements show the importance of morphology and structure in templating interactions for organic electronics applications.	May 2015
I19-Small Molecule Single Crystal Diffraction	Structural, electronic and magnetic properties of metal phthalocyanines Luke Rochford Show Abstract ▼ Abstract: Metal phthalocyanines (MPcs) prepared as single crystals, polycrystalline powders and thin films have been analysed using a combination of surface science techniques, diffraction based structural characterisation and magnetic characterisation. Vanadium oxide phthalocyanine (VOPc) prepared as thin films on the (111) surface of gold, silver and copper is analysed by (STM) low energy electron diffraction (LEED) and ultraviolet photoemission spectroscopy (UPS). Similar surface and electronic structure is observed on gold and silver, but profoundly different assembly and electronic properties were observed on copper. The effect of increasing the substrate temperature during growth on the structure and morphology of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc) is investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). An evaporated copper iodide (CuI) structural template layer is also used to alter the arrangement of FePc molecules in thin films. The single crystal structure of fluorinated copper phthalocyanine (F16CuPc) is re-determined using synchrotron X-ray diffraction. Thin films of F16CuPc grown on graphene oxide supports are analysed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). This allows assignment of both crystal structure and texture in polycrystalline thin films of a variety of thicknesses. F16CuPc is also analysed using superconducting quantum interference (SQUID) magnetometry in both powder and thin film morphologies. 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) structural template layers are used to alter the orientation of crystallites and the effect of this on the magnetic properties are analysed.	Sep 2013
	Resolving the Nanoscale Morphology and Crystallographic Structure of Molecular Thin Films: F16CuPc on Graphene Oxide Priyanka A. Pandey , Luke Rochford , Dean S. Keeble , Jonathan P. Rourke , Tim S. Jones , Richard Beanland , Neil R. Wilson Chemistry Of Materials 24 (7), 1365 - 1370 DOI: 10.1021/cm300073v Show Abstract ▼ Abstract: Electron microscopy and diffraction are used to examine the nanoscale structure and molecular orientation in molecular films down to nominally monolayer thickness. The films studied consist of the planar n-type molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) directly deposited onto graphene oxide (GO) membranes by organic molecular beam deposition. The graphene oxide support crucially provides the strength and low background required to analyze the crystal structure and morphology of even nominally monolayer thick films and is of relevance for molecular electronic applications. The crystal structure of the F16CuPc polymorph is solved by X-ray diffraction of single crystals and used to analyze the electron diffraction patterns from the thin-films, revealing that the F16CuPc molecules assemble with their molecular plane oriented perpendicular to the GO. There is no evidence for changes in the unit cell with film thickness, although the thinnest films show the greatest disorder in molecular packing. Direct deposition of molecular materials on low contrast and combined with electron and scanning probe microscopy is thus shown to be a powerful technique for elucidating structure in nanostructured organic thin films.	Apr 2012

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