Search Results

You searched for all publications:

with publication states 'Published (Approved)'
published in journal 'Journal Of Physical Chemistry C'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

85 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I09-Surface and Interface Structural Analysis	The molecule-metal bond of alternant versus nonalternant aromatic systems on coinage metal surfaces: naphthalene versus azulene on Ag(111) and Cu(111) Benedikt P. Klein , Juliana M. Morbec , Markus Franke , Katharina K. Greulich , Malte Sachs , Shayan Parhizkar , Francois C. Bocquet , Martin Schmid , Samuel J. Hall , Reinhard J. Maurer , Bernd Meyer , Ralf Tonner , Christian Kumpf , Peter Kratzer , J. Michael Gottfried The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b08824 Diamond Proposal Number(s): [16259] Show Abstract ▼ Abstract: Interfaces between polycyclic π-electron systems and metals play prominent roles in organic or graphene-based (opto)electronic devices, in which performance-related parameters depend critically on the properties of metal/semiconductor contacts. Here, we explore how the topology of the π-electron system influences the bonding and the electronic properties of the interface. We use azulene as a model for nonalternant pentagon-heptagon (5-7) ring pairs and compare it to its isomer naphthalene, which represents the alternant 6-6 ring pair. Their coverage-dependent interaction with Ag(111) and Cu(111) surfaces was studied with the normal-incidence X-ray standing wave (NIXSW) technique, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, UV and X-ray photoelectron spectroscopy (UPS, XPS), and density functional theory (DFT). Coverage-dependent adsorption heights and spectroscopic data reveal that azulene forms shorter interfacial bonds than naphthalene and engages in stronger electronic interactions with both surfaces. These differences are more pronounced on Cu. Increasing coverages lead to larger adsorption heights, indicating bond weakening by intermolecular repulsion. The extensive DFT calculations include dispersive interactions using: (1) the DFT-D3 scheme, (2) the vdWsurf correction based on DFT-TS, (3) a Many-Body Dispersion (MBD) correction scheme, and (4) the D3surf scheme. All methods predict the adsorption heights reasonably well with an average error below 0.1 Å. The stronger bond of azulene is attributed to its nonalternant topology, which results in a reduced HOMO-LUMO gap and brings the LUMO energetically close to the Fermi energy of the metal, causing stronger hybridization with electronic states of the metal surfaces.	Nov 2019
I19-Small Molecule Single Crystal Diffraction	Achieving conformational control in RTP and TADF emitters by functionalization of the central core Nadzeya A. Kukhta , Rongjuan Huang , Andrei S. Batsanov , Martin R. Bryce , Fernando B. Dias The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b08238 Diamond Proposal Number(s): [11145] Show Abstract ▼ Abstract: Three new symmetrical donor–acceptor–donor (D–A–D)-type molecules were prepared with phenothiazine (PTZ) as electron donors and 9,9-dimethylthioxanthene (TX) as the electron acceptor. The PTZ groups are attached at different positions on the acceptor core – ortho or meta to the sulfur of TX. The molecules have been characterized by X-ray crystallography, in-depth photophysical studies and theoretical calculations. This series provides new insights into how molecular functionalization and intramolecular charge transfer determines the singlet-triplet gap ΔEST. Two of the molecules have weak D/A decoupling and a relatively large ΔEST of 0.52 eV which prohibits the upconversion of triplet excitons to the singlet state, showing strong room temperature phosphorescence (RTP). When the TX acceptor strength is enhanced by the attachment of benzoyl substituents a very small ΔEST of <0.01 eV is observed. In this case excitons in the triplet state can be efficiently upconverted to the singlet state via reverse intersystem crossing (RISC) resulting in thermally activated delayed fluorescence (TADF). TADF and RTP are unambiguously assigned by distinctive photophysical data, notably a comparison of degassed and aerated luminescence spectra, temperature-dependent time-resolved fluorescence decays and power dependence of the intensity of delayed emission (for the TADF emitter).	Oct 2019
	Atom probe tomography of Au-Cu bimetallic nanoparticles synthesized by inert gas condensation Qifeng Yang , Mohsen Danaie , Neil Young , Vicky Broadley , David E. Joyce , Tomas L. Martin , Eric Marceau , Michael P. Moody , Paul A. J. Bagot The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b09340 Show Abstract ▼ Abstract: The Inert Gas Condensation method (IGC) produces multimetallic nanoparticles in a metastable state that may exhibit heterogeneities of size, structure and composition. The deposition of IGC-fabricated nanoparticles on substrates allows for a detailed characterization by combination of aberration-corrected transmission electron microscopy (TEM) and Atom Probe Tomography (APT). Multiple particle monitoring and high-resolution TEM give access to the size distribution of Au-Cu nanoparticles (<10nm in diameter, bimodal distribution). TEM and APT show that the alloying between Cu and Au may stabilize the Ih structure for smaller particles (<4nm). Combining HR-STEM/EDX and 3D composition analysis by APT reveals that an excess of Cu may be present in a shell around the larger particles (>7nm), while Cu is more randomly distributed in smaller particles.	Oct 2019
I15-1-X-ray Pair Distribution Function (XPDF)	Comparative microstructural analysis of non-graphitic carbons by wide-angle X-ray and neutron scattering Torben Pfaff , Felix M. Badaczewski , Marc Oliver Loeh , Alexandra Franz , Jens-uwe Hoffmann , Manfred Reehuis , Wolfgang G. Zeier , Bernd M. Smarsly The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b03590 Diamond Proposal Number(s): [13560] Show Abstract ▼ Abstract: Non-graphitic carbons (NGCs) represent the most abundant class of \(sp^2\)-hybridized carbon materials (coal, char coal, activated carbon, etc.). These carbons consist of small graphene layer stacks possessing significant structural disorder both in the single graphene sheets and the stacking. In this study an advanced evaluation approach for the wide-angle neutron scattering (WANS) was developed, based on the method introduced by Ruland and Smarsly (2002). In particular, we elucidated if and how the enhanced WANS data quality and larger values of the modulus of the scattering vector \(s\)-range affect the accuracy and the values of the size and disorder parameters - being fitting parameters by themselves - in comparison to wide-angle x-ray scattering (WAXS), which is usually performed by laboratory equipment. We find a reasonable agreement for the parameters \(L_\mathrm{a}\) and \(L_\mathrm{c}\), i.e. the lateral dimension and stack height, within the error bars, while for the disorder parameters different results for WAXS and WANS were found, the origin of which is discussed. Thus, this study addresses the general issue of how reliably microstructural parameters can be determined from WAXS/WANS, by fitting simulated WAXS and WANS curves, which are quality-impaired by added Gaussion noise at different levels and cut-off at different \(s\)-values. From this analysis we estimated the minimal data quality required for a reliable NGC microstructural analysis based on WAXS/WANS. As an important finding, these simulations show that typical, standard WAXS laboratory setups are sufficient to provide reliable values for the most relevant structural parameters. Furthermore, pair-distribution function (PDF) analyses were performed on WAXS data obtained from a Synchrotron facility. Comparing PDF and WAXS/WANS fitting analysis thus suggests the presence of small highly ordered oligoaromatic domains embedded in the larger graphene sheets, questioning the classical view on the NGC microstructure.	Jul 2019
	Corrosion of gold by a nanoscale gold and copper belt-like structure Hidetaka Sawada , Konstantin B. Borisenko , Masahide Shima , Konomi Ikita , Hiroki Hashiguchi , Ichiro Onishi , Eiji Okunishi , Angus I. Kirkland The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b04344 Show Abstract ▼ Abstract: We report the observation of corrosion of gold at the nanoscale, in which nm-sized gold can be corroded in air in the presence of copper at room temperature during ageing to form a compound of gold with residual copper. The compound is a nanoscale belt-like two-dimensional structure that can be prepared from gold nanoparticles. Using high-resolution electron microscopy and chemical analyses, we show that the structure consists of alternating rows of gold and copper atoms. The atomic columns of gold are arranged in rows separated by 0.5 nm and the structure extends in a perpendicular direction to these. DFT calculations of an atomic model of this two-dimensional material consisting of gold, copper, and oxygen suggest that it is a narrow bandgap semiconductor. This belt-like structure, growing around Au fine wire bonding in nano devices, may cause failure in the electric contact in nanodevices. Thus, this study has direct relevance to the use of gold as a contact material in semiconductor devices. In addition, possible future applications as additives in organic solar cells are discussed.	Jul 2019
I09-Surface and Interface Structural Analysis	Water splitting on Ti-oxide terminated SrTiO3(001) Vladyslav Solokha , Debi Garai , Axel Wilson , David A. Duncan , Pardeep K. Thakur , Kurt Hingerl , Jorg Zegenhagen The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b01730 Diamond Proposal Number(s): [15132] Open Access Show Abstract ▼ Abstract: Combining X-ray photoelectron spectroscopy with the standing wave technique we investigated adsorption of a monolayer of water on Ti-oxide terminated SrTiO3(001) in ultra-high vacuum (UHV). At room temperature, the surface is water free but hydroxylated. A quarter monolayer of hydroxyl is tightly bound (1.85 ± 0.06) Å above the TiO2 surface. Deposited at low temperature, a monolayer of water adsorbs with the oxygen located (2.55 ± 0.2) Å above the surface, apparently close to atop Ti, but H2O is unstable at 200K. A fraction desorbs, in part under the X-ray beam, but a major fraction of H2O dissociates immediately, with the liberated hydrogen most likely attaching to a surface oxygen. The produced hydroxyls bind only loosely to the surface, are unstable at 200K and rapidly desorb once the surface is water-free. Although our study was conducted in UHV, the presented results suggests that Ti-oxide terminated SrTiO3(001) may possess a high catalytic activity toward hydrolysis under realistic conditions.	Jun 2019
I15-Extreme Conditions	The structure of CaSO4 nanorods - the precursor of gypsum Tomasz M. Stawski , Alexander E. S. Van Driessche , Rogier Besselink , Emily H. Byrne , Paolo Raiteri , Julian D. Gale , Liane G. Benning The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b04268 Diamond Proposal Number(s): [11320] Show Abstract ▼ Abstract: The understanding of the gypsum (CaSO4∙2H2O) formation pathway from aqueous solutions has been the subject of intensive research in the last couple of years. This interest stems from the fact that gypsum appears to fall into a broader category of crystalline materials whose formation does not follow classical nucleation and growth theories. The pathways involve transitory precursor cluster species, yet the actual structural properties of such clusters are not very well understood. Here, we show how in situ high-energy X-ray diffraction (HEXD) experiments and molecular dynamics (MD) simulations can be combined to derive the structure of small CaSO4 clusters, which are precursors to crystalline gypsum. We fitted several plausible structures to the derived pair distribution functions (PDFs), and explored their dynamic properties using unbiased MD based on both rigid-ion and polarizable force-fields. Determination of the structure and (meta)stability of the primary species is important both from a fundamental and applied perspective; for example, this will allow for improved design of additives for greater control of the nucleation pathway.	Jun 2019
I09-Surface and Interface Structural Analysis	Lifting epitaxial graphene by intercalation of alkali metals Caio C. Silva , Jiaqi Cai , Wouter Jolie , Daniela Dombrowski , Ferdinand H. Farwick Zum Hagen , Antonio J. Martinez-galera , Christoph Schlueter , Tien-lin Lee , Carsten Busse The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b02442 Diamond Proposal Number(s): [9012, 12558] Show Abstract ▼ Abstract: We study the effect of alkali metal intercalation (Cs and Li) on the geometry of graphene on Ir(111) using the x-ray standing waves technique. For both alkali metals, the increase in the mean height of the carbon layer does not depend on the lateral structure or the density of the intercalated layer. For Li, full delamination of graphene from the metal substrate is found already for a small amount of intercalant. Even though Lithium lifts graphene to a smaller height, it is much more efficient in ironing out the corrugation of pristine graphene on Ir(111).	May 2019
I07-Surface & interface diffraction	Water-induced reversal of the TiO2 (011)-(2x1) surface reconstruction: observed with in situ surface X-ray diffraction Hadeel Hussain , Mahmoud H. M. Ahmed , Xavier Torrelles , David Grinter , Gregory Cabailh , Oier Bikondoa , Christopher Nicklin , Ulrich Aschauer , Robert Lindsay , Geoff Thornton The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b04383 Diamond Proposal Number(s): [8952] Show Abstract ▼ Abstract: The (011) termination of rutile TiO2 is reported to be particularly effective for photocatalysis. Here the structure of the interface formed between this substrate and water is revealed using surface X-ray diffraction. While the TiO2(011) surface exhibits a (2x1) reconstruction in ultra-high vacuum, this is lifted in the presence of a multilayer of water at room temperature. This change is driven by the formation of Ti-OH at the interface, which has a bond distance of 1.93 ± 0.02 Å. The experimental solution is in good agreement with density functional theory and first principles molecular dynamics calculations. These results point to the important differences that can arise between the structure of oxide surfaces in ultra-high vacuum and technical environments and will ultimately lead to an atomistic understanding of the photocatalytic process of water splitting on TiO2 surfaces.	May 2019
I19-Small Molecule Single Crystal Diffraction	Persistent dimer emission in thermally activated delayed fluorescence materials Marc K. Etherington , Nadzeya A. Kukhta , Heather F. Higginbotham , Andrew Danos , Aisha N. Bismillah , David R. Graves , Paul R. Mcgonigal , Nils Haase , Antonia Morherr , Andrei S. Batsanov , Christof Pflumm , Vandana Bhalla , Martin R. Bryce , Andrew P. Monkman The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.9b01458 Diamond Proposal Number(s): [11145] Show Abstract ▼ Abstract: We expose significant changes in emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise through the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electrolumines-cence. The dimer species is sensitive to the sample preparation method and its enduring presence contributes to the widely reported concentration-mediated redshift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has significant implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The significant dimer-ization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consid-eration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.	Apr 2019

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User