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47 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I07-Surface & interface diffraction	Effect of anionic lipids on mammalian plasma cell membrane properties Alexandra L. Martin , Philip N. Jemmett , Thomas Howitt , Mary H. Wood , Andrew W. Burley , Liam R. Cox , Timothy R. Dafforn , Rebecca J. L. Welbourn , Mario Campana , Maximilian W. A. Skoda , Joseph J. Thompson , Hadeel Hussain , Jonathan L. Rawle , Francesco Carla , Christopher L. Nicklin , Thomas Arnold , Sarah L. Horswell Langmuir DOI: 10.1021/acs.langmuir.2c03161 Diamond Proposal Number(s): [14670, 16423, 19542] Open Access Show Abstract ▼ Abstract: The effect of lipid composition on models of the inner leaflet of mammalian cell membranes has been investigated. Grazing incidence X-ray diffraction and X-ray and neutron reflectivity have been used to characterize lipid packing and solvation, while electrochemical and infrared spectroscopic methods have been employed to probe phase behavior in an applied electric field. Introducing a small quantity of the anionic lipid dimyristoylphosphatidylserine (DMPS) into bilayers of zwitterionic dimyristoylphosphatidylethanolamine (DMPE) results in a significant change in the bilayer response to an applied field: the tilt of the hydrocarbon chains increases before returning to the original tilt angle on detachment of the bilayer. Equimolar mixtures, with slightly closer chain packing, exhibit a similar but weaker response. The latter also tend to incorporate more solvent during this electrochemical phase transition, at levels similar to those of pure DMPS. Reflectivity measurements reveal greater solvation of lipid layers for DMPS > 30 mol %, matching the greater propensity for DMPS-rich bilayers to incorporate water. Taken together, the data indicate that the range of 10–35 mol % DMPS provides optimum bilayer properties (in flexibility and function as a barrier), which may explain why the DMPS content of cell membranes tends to be found within this range.	Feb 2023
I07-Surface & interface diffraction	Direct experimental determination of Ag adatom locations in TCNQ-Ag 2D metal–organic framework on Ag(111) Philip J. Mousley , Luke A. Rochford , Hadeel Hussain , Stefania Moro , Pengcheng Ding , Gavin R. Bell , Giovanni Costantini , Christopher Nicklin , D. Phil Woodruff The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.2c07683 Diamond Proposal Number(s): [24284] Open Access Show Abstract ▼ Abstract: A previous investigation of the structure of TCNQ adsorbed on Ag(111) using normal-incidence X-ray standing waves (NIXSW) and density functional theory (DFT) provided indirect evidence that Ag adatoms must be incorporated into the molecular overlayer. New surface X-ray diffraction (SXRD) results, presented here, provide direct evidence for the presence and location of these Ag adatoms and clearly distinguishes between two alternative models of the adatom registry favored by two different DFT studies.	Feb 2023
Optics	An analytical approach to designing a future Nano-ARPES beamline for Diamond-II A. C. Walters , L. Alianelli , H. Wang , M. D. Watson , C. Cacho , C. Nicklin , K. Sawhney 14th International Conference on Synchrotron Radiation Instrumentation (SRI 2021) DOI: 10.1088/1742-6596/2380/1/012039 Open Access Show Abstract ▼ Abstract: Angle-resolved photoemission spectroscopy (ARPES) is a powerful method for measuring the electronic band structure of solids. Diamond Light Source is planning to build a multibend-achromat (MBA) synchrotron – Diamond-II - which will provide an almost diffraction-limited photon source in the vacuum-ultraviolet photon energy range. The improved emittance and higher coherence of MBA synchrotrons means that samples with features smaller than 1 µm can be readily studied using ARPES, provided the beamline is designed to take full advantage of the new photon source. We have developed an analytical method for optimising the optical design of a future Nano-ARPES beamline for Diamond-II. Our method enables one to explore large regions of parameter space for a beamline design in an unbiased and systematic way, with minimal requirements on computing power. We believe that the analytical method presented here will be a useful tool for synchrotron beamline designers, as it allows many beamline characteristics to be simulated quickly while working within any practical limitations.	Dec 2022
I07-Surface & interface diffraction	Influence of the lipid backbone on electrochemical phase behavior Philip N. Jemmett , David C. Milan , Richard J. Nichols , Thomas Howitt , Alexandra L. Martin , Thomas Arnold , Jonathan L. Rawle , Christopher L. Nicklin , Timothy R. Dafforn , Liam R. Cox , Sarah L. Horswell Langmuir 10 DOI: 10.1021/acs.langmuir.2c02370 Diamond Proposal Number(s): [15539, 18202] Show Abstract ▼ Abstract: Sphingolipids are an important class of lipids found in mammalian cell membranes with important structural and signaling roles. They differ from another major group of lipids, the glycerophospholipids, in the connection of their hydrocarbon chains to their headgroups. In this study, a combination of electrochemical and structural methods has been used to elucidate the effect of this difference on sphingolipid behavior in an applied electric field. N-Palmitoyl sphingomyelin forms bilayers of similar coverage and thickness to its close analogue di-palmitoyl phosphatidylcholine. Grazing incidence diffraction data show slightly closer packing and a smaller chain tilt angle from the surface normal. Electrochemical IR results at low charge density show that the difference in tilt angle is retained on deposition to form bilayers. The bilayers respond differently to increasing electric field strength: chain tilt angles increase for both molecules, but sphingomyelin chains remain tilted as field strength is further increased. This behavior is correlated with disruption of the hydrogen-bonding network of small groups of sphingomyelin molecules, which may have significance for the behavior of molecules in lipid rafts in the presence of strong fields induced by ion gradients or asymmetric distribution of charged lipids.	Nov 2022
I07-Surface & interface diffraction I09-Surface and Interface Structural Analysis	Direct experimental evidence for substrate adatom incorporation into a molecular overlayer Philip J. Mousley , Luke A. Rochford , Paul T. P. Ryan , Philip Blowey , James Lawrence , David A. Duncan , Hadeel Hussain , Billal Sohail , Tien-Lin Lee , Gavin R. Bell , Giovanni Costantini , Reinhard J. Maurer , Christopher Nicklin , D. Phil Woodruff The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.2c01432 Diamond Proposal Number(s): [14884, 4884] Open Access Show Abstract ▼ Abstract: While the phenomenon of metal substrate adatom incorporation into molecular overlayers is generally believed to occur in several systems, the experimental evidence for this relies on the interpretation of scanning tunneling microscopy (STM) images, which can be ambiguous and provides no quantitative structural information. We show that surface X-ray diffraction (SXRD) uniquely provides unambiguous identification of these metal adatoms. We present the results of a detailed structural study of the Au(111)-F4TCNQ system, combining surface characterization by STM, low-energy electron diffraction, and soft X-ray photoelectron spectroscopy with quantitative experimental structural information from normal incidence X-ray standing wave (NIXSW) and SXRD, together with dispersion-corrected density functional theory (DFT) calculations. Excellent agreement is found between the NIXSW data and the DFT calculations regarding the height and conformation of the adsorbed molecule, which has a twisted geometry rather than the previously supposed inverted bowl shape. SXRD measurements provide unequivocal evidence for the presence and location of Au adatoms, while the DFT calculations show this reconstruction to be strongly energetically favored.	Apr 2022
I07-Surface & interface diffraction	Interfacial rearrangements and strain evolution in the thin film growth of ZnPc on glass Thomas L. Derrien , Andreas E. Lauritzen , Pascal Kaienburg , Ellis Hancox , Chris Nicklin , Moritz Riede Physical Review Materials 6 DOI: 10.1103/PhysRevMaterials.6.033401 Diamond Proposal Number(s): [20426] Open Access Show Abstract ▼ Abstract: We report on the characterization of the growth of vacuum-deposited zinc phthalocyanine (ZnPc) thin films on glass through a combination of in situ grazing incidence x-ray scattering, x-ray reflectivity, and atomic force microscopy. We found that the growth at room temperature proceeds via the formation of two structurally unique substrate-induced interfacial layers, followed by the growth of the γ -ZnPc polymorph thereafter (thickness ≈ 1.0 nm). As the growth of the bulk γ -ZnPc progresses, a substantial out-of-plane lattice strain ( ≈ 15 % relative to γ -ZnPc powder) is continually relaxed during the thin film growth. The rate of strain relaxation was slowed after a thickness of ≈ 13 nm, corresponding to the transition from layer growth to island growth. The findings reveal the real-time microstructural evolution of ZnPc and highlight the importance of substrate-induced strain on thin film growth.	Mar 2022
	Synchrotron techniques for African research and technology: a step-change in structural biology and energy materials Chris Nicklin , Rebekka Stredwick , Trevor Sewell Synchrotron Radiation News DOI: 10.1080/08940886.2022.2043684 Open Access Show Abstract ▼ Abstract: In June 2021, scientists celebrated the numerous achievements of a unique collaboration between researchers from the UK and Africa and the UK’s national synchrotron, Diamond Light Source [1]. The Synchrotron Techniques for African Research and Technology (START) [2] programme was funded by a 3-year, £3.7 M Global Challenges Research Fund (GCRF) grant provided by the UK Research and Innovation’s Science and Technology Facilities Council (STFC), with the aim of improving researchers’ access to Diamond. The grant’s remit was to fund research posts focusing on two research areas crucial to African sustainable development: energy materials and structural biology. The aim was to align the project with key United Nations Sustainable Development Goals for health (SDG 3), energy (SDG 7), climate (SDG 13), and life-long learning (SDG 4), amongst others. In this article, we report on highlights of the programme and what’s next on the horizon for START.	Mar 2022
I07-Surface & interface diffraction	Structure of strained low‐dimensional Sb by in situ surface X‐ray diffraction Philip J. Mousley , Christopher W. Burrows , Chris Nicklin , Gavin R. Bell Physica Status Solidi (b) DOI: 10.1002/pssb.202100432 Diamond Proposal Number(s): [13769] Open Access Show Abstract ▼ Abstract: Antimony ultra-thin films in tensile strain are grown on InAs(111)B substrates and studied in situ using surface X-ray diffraction. The detailed atomic structures of two highly crystalline Sb(0001) films are derived, with thicknesses of 19 and 4 bilayers. Features considered in structural modelling include interfacial intermixing, surface roughness, individual layer relaxations and rotational twin domains (RTDs). The 4-bilayer film shows significant structural relaxation in every layer, while both films include RTDs. The results are discussed in relation to the topological properties of low-dimensional Sb.	Jan 2022
I07-Surface & interface diffraction	In-situ observations of the growth mode of vacuum deposited α-sexithiophene Thomas L. Derrien , Andreas E. Lauritzen , Pascal Kaienburg , Josue F. M. Hardigree , Christopher Nicklin , Moritz K. Riede The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.0c00447 Diamond Proposal Number(s): [20426, 24871] Open Access Show Abstract ▼ Abstract: The real-time morphological evolution of vacuum deposited α-sexithiophene (α-6T) on a weakly interacting (glass) substrate at ambient temperature is reported. In-situ grazing incidence small angle X-ray scattering (GISAXS) enabled the observation of nanoscale aggregates while in-situ grazing incidence wide angle scattering (GIWAXS) allowed the study of the molecular-scale morphology. The in-situ GISAXS measurements revealed that the α-6T growth proceeds via a Stranski-Krastanov mode, whereby 2-4 complete monolayers are deposited followed by subsequent layers formed via island growth. In-situ GIWAXS also showed the evolution of the polymorph composition during the thin film growth. Initially the disordered β-phase and the low-temperature (LT) phase are deposited in nearly equal proportion until a thickness of 8 nm whereby the LT-phase begins to dominate until a final α-6T thickness of 50 nm where the scattering intensity of the LT-phase is more than double that of the β-phase. The change in polymorph composition coincided with an increase in the LT-phase d-spacing, indicating a lattice strain relief as the thin film moves from surface to bulk mediated growth. The GISAXS findings were confirmed through direct imaging using ex-situ atomic force microscopy (AFM) at various thicknesses revealing the existence of both initial monolayers and intermediate and final island morphologies. The findings reveal the real-time morphological evolution of α-6T across both the molecular scale and the nanoscale and highlight the role of strain in polymorph growth. Due to the importance of thin film microstructure in device performance, it is expected that these results will aid in the development of the structure-property relationships necessary to realise the full potential of organic electronics.	May 2020
I07-Surface & interface diffraction	Spin splitting and strain in epitaxial monolayer WSe2 on graphene H. Nakamura , A. Mohammed , Ph. Rosenzweig , K. Matsuda , K. Nowakowski , K. Küster , P. Wochner , S. Ibrahimkutty , U. Wedig , H. Hussain , J. Rawle , C. Nicklin , B. Stuhlhofer , G. Cristiani , G. Logvenov , H. Takagi , U. Starke Physical Review B 101 DOI: 10.1103/PhysRevB.101.165103 Diamond Proposal Number(s): [18887] Open Access Show Abstract ▼ Abstract: We present the electronic and structural properties of monolayer WSe 2 grown by pulsed-laser deposition on monolayer graphene (MLG) on SiC. The spin splitting in the WSe 2 valence band at ¯¯¯ K was Δ SO = 0.469 ± 0.008 eV, as determined by angle-resolved photoemission spectroscopy. Synchrotron-based grazing-incidence in-plane x-ray diffraction (XRD) revealed the in-plane lattice constant of monolayer WSe 2 to be a WSe 2 = 3.2757 ± 0.0008 Å. This indicates a lattice compression of − 0.19 % relative to bulk WSe 2 . By using the experimentally determined graphene lattice constant ( a MLG = 2.4575 ± 0.0007 Å), we found that a 3 × 3 unit cell of the slightly compressed WSe 2 is perfectly commensurate with a 4 × 4 graphene lattice with a mismatch below 0.03%, which could explain why the monolayer WSe 2 is compressed on MLG. From XRD and first-principles calculations, we conclude that the observed size of strain will affect Δ SO only on the order of a few meV. In addition, angle-resolved, ultraviolet, and x-ray photoelectron spectroscopies shed light on the band alignment between WSe 2 and MLG/SiC and indicate electron transfer from graphene to the WSe 2 monolayer. As further revealed by atomic force microscopy, the WSe 2 island size depends on the number of carbon layers on top of the SiC substrate. This suggests that the epitaxy of WSe 2 favors the weak van der Waals interactions with graphene, while it is perturbed by the influence of the SiC substrate and its carbon buffer layer.	Apr 2020

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