James Downes

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

Publisher: American Physical Society (APS)

Date: 15-05-2014

DOI: 10.1103/PHYSREVB.89.195422

Electronic structure of the organic semiconductor vanadyl phthalocyanine (VO-Pc)

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B613274J

Observation of multiple Zhang-Rice excitations in a correlated solid: Resonant inelastic X-ray scattering study of Li ₂ CuO

Publisher: IOP Publishing

Date: 27-07-2007

DOI: 10.1209/0295-5075/79/47012

Photochemical etching of carbonyl groups from a carbon matrix

Publisher: American Physical Society (APS)

Date: 08-01-2019

DOI: 10.1103/PHYSREVLETT.122.016802

Configurable heralded two-photon states on a chip

Publisher: OSA

Date: 2016

DOI: 10.1364/FIO.2016.FTU3G.3

Optical conductivity and x-ray absorption and emission study of the band structure of MnN films

Publisher: American Physical Society (APS)

Date: 28-11-2005

DOI: 10.1103/PHYSREVB.72.205127

Surface degradation of InxGa1−xN thin films by sputter-anneal processing: A scanning photoemission microscope study

Publisher: AIP Publishing

Date: 23-10-2003

DOI: 10.1063/1.1617356

Abstract: The effects of nitrogen ion sputtering and thermal anneal processing on the surface electronic structure of the ternary III–V semiconductor In0.12Ga0.88N have been studied using scanning photoemission microscopy. No phase separation of the material is observed for annealing temperatures up to 650 °C. However, s les annealed at 700 °C for 5 h show clear evidence of phase separation. Furthermore, annealing at these temperatures with the s le surface directly exposed to ultrahigh vacuum produces a surface greatly deficient in In and with considerable surface roughness. This can be circumvented by using a sacrificial s le in physical contact with the film to artificially increase the local vapor pressure of Ga, In, and N during annealing.

The local electronic structure of tin phthalocyanine studied by resonant soft X-ray emission spectroscopies

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.APSUSC.2008.07.058

Controlling the motional quality factor of a diamagnetically levitated graphite plate

Publisher: AIP Publishing

Date: 27-02-2023

DOI: 10.1063/5.0133242

Abstract: Researchers seek methods to levitate matter for a wide variety of purposes, ranging from exploring fundamental problems in science through to developing new sensors and mechanical actuators. Many levitation techniques require active driving and most can only be applied to objects smaller than a few micrometers. Diamagnetic levitation has the strong advantage of being the only form of levitation which is passive, requiring no energy input, while also supporting massive objects. Known diamagnetic materials which are electrical insulators are only weakly diamagnetic and require large magnetic field gradients to levitate. Strong diamagnetic materials which are electrical conductors, such as graphite, exhibit eddy d ing, restricting motional freedom and reducing their potential for sensing applications. In this work, we describe a method to engineer the eddy d ing while retaining the force characteristics provided by the diamagnetic material. We study, both experimentally and theoretically, the motional d ing of a magnetically levitated graphite plate in high vacuum and demonstrate that one can control the eddy d ing by patterning the plate with through-slots which interrupt the eddy currents. We find that we can control the motional quality factor over a wide range with excellent agreement between the experiment and numerical simulations.

Tunable electrical and optical properties of hafnium nitride thin films

Publisher: AIP Publishing

Date: 15-02-2010

DOI: 10.1063/1.3327329

Abstract: We report structural and electronic properties of epitaxial hafnium nitride films grown on MgO by plasma-assisted pulsed laser deposition. The electronic structure measured using soft x-ray absorption and emission spectroscopy is in excellent agreement with the results of a band structure calculation. We show that by varying the growth conditions we can extend the films’ reflectance further toward the UV, and we relate this observation to the electronic structure.

Design and fabrication of reconfigurable laser-written waveguide circuits

Publisher: The Optical Society

Date: 19-12-2017

DOI: 10.1364/OE.25.033056

Electronic structures of wurtzite gan with ga and n vacancies

Publisher: IOP Publishing

Date: 28-06-2007

DOI: 10.1088/0256-307X/24/7/072

Enhanced etch rate of deep-UV laser induced etching of diamond in low pressure conditions

Publisher: AIP Publishing

Date: 14-09-2020

DOI: 10.1063/5.0020405

Abstract: Ultraviolet laser-induced etching is a method of machining and nanostructuring diamond surfaces in which carbon is removed from the surface via a photochemical process involving oxygen. We show here that using a dry source of oxygen at pressures in the range of 0.01–1 Torr leads to a 10-fold increase in the etch rate compared to etching in atmospheric air. The enhanced etch rate is also found to be accompanied by a marked change in the nanopatterned surface morphology. We developed a rate equation model for the etch rate that provides good agreement with measurements for pressures up to approximately 0.1 Torr. For higher pressures, the reduced etch rate and departure from the model are attributed to the contamination of the diamond surface by trace amounts of water vapor, introduced as an impurity from the gas sources. The results provide a method for markedly increasing the etch rate, as well as a better understanding of the role of gas impurities on the etch mechanism and emergent nanopattern formation.

Photocurrent enhancement of graphene photodetectors by photon tunneling of light into surface plasmons

Publisher: IOP Publishing

Date: 18-09-2017

DOI: 10.1088/2040-8986/AA86D3

Optical and electronic characterization of diamond surfaces exposed to UV laser radiation

Publisher: Optica Publishing Group

Date: 2020

DOI: 10.1364/CLEOPR.2020.P1_18

Abstract: Low power UV laser radiation has been previously found to etch diamond surfaces via a multiphoton process. Here we show that UV exposure also increases the NV photoluminescence and enhances hydrogen-terminated surface conductivity.

Surface electronic structure of p-type GaN(0001̄)

Publisher: Elsevier BV

Date: 11-2000

DOI: 10.1016/S0039-6028(00)00820-7

Electronic excitations in vanadium oxide phthalocyanine studied via resonant soft X-ray emission and resonant inelastic X-ray scattering

Publisher: Elsevier BV

Date: 09-2005

DOI: 10.1016/J.CPLETT.2005.07.066

On-chip generation of heralded photon-number states

Publisher: Springer Science and Business Media LLC

Date: 24-10-2016

DOI: 10.1038/SREP35975

Abstract: Beyond the use of genuine monolithic integrated optical platforms, we report here a hybrid strategy enabling on-chip generation of configurable heralded two-photon states. More specifically, we combine two different fabrication techniques, i.e. , non-linear waveguides on lithium niobate for efficient photon-pair generation and femtosecond-laser-direct-written waveguides on glass for photon manipulation. Through real-time device manipulation capabilities, a variety of path-coded heralded two-photon states can be produced, ranging from product to entangled states. Those states are engineered with high levels of purity, assessed by fidelities of 99.5 ± 8% and 95.0 ± 8%, respectively, obtained via quantum interferometric measurements. Our strategy therefore stands as a milestone for further exploiting entanglement-based protocols, relying on engineered quantum states, and enabled by scalable and compatible photonic circuits.

Electronic structure of the organic semiconductor copper tetraphenylporphyrin (CuTPP)

Publisher: Elsevier BV

Date: 11-2009

DOI: 10.1016/J.APSUSC.2009.08.048

Electronic structure in thin film organic semiconductors studied using soft X-ray emission and resonant inelastic X-ray scattering

Publisher: Elsevier BV

Date: 10-2006

DOI: 10.1016/J.TSF.2005.12.221

Magneto-mechanical trapping of micro-diamonds at low pressures

Publisher: AIP Publishing

Date: 04-02-2019

DOI: 10.1063/1.5066065

Abstract: A number of quantum technologies require macroscopic mechanical oscillators possessing ultra-high motional Q-factors. These can be used to explore the macroscopic limits of quantum mechanics, to develop quantum sensors and to test the quantum nature of gravity. One approach is to trap nanometer to micron-sized particles in 3D however, the use of ion or optical traps suffers from a number of difficulties including electrodynamic noise due to patch fields, damage to the particles due to unwanted laser heating, or difficulty in reaching low pressures due to particle loss. In this work, we report a completely passive, magnetic trap which confines a micro-diamond in 3D and which requires no active power—optical or electrical. We design, model, fabricate, and test the operation of our magneto-mechanical trap and experimentally demonstrate trapping down to ∼0.1 Torr. We measure the position fluctuation of the trapped micro-diamond as a function of pressure and find good agreement with Brownian theory.

Electronic structure near the Fermi level of the organic semiconductor copper phthalocyanine

Publisher: Elsevier BV

Date: 05-2004

DOI: 10.1016/J.CPLETT.2004.04.026

Measurements of anisotropic thermopower of magnetically aligned YBa2Cu3O7−δ ceramics: evidence of successful texturing techniques

Publisher: Elsevier BV

Date: 07-2003

DOI: 10.1016/S0921-4534(03)00809-8

Electronic band structure information of GdN extracted from x-ray absorption and emission spectroscopy

Publisher: AIP Publishing

Date: 18-01-2010

DOI: 10.1063/1.3291057

RESONANT SOFT X-RAY EMISSION SPECTROSCOPY OF V₂O₃, VO₂andNaV₂O₅

Publisher: World Scientific Pub Co Pte Lt

Date: 04-2002

DOI: 10.1142/S0218625X02003822

Abstract: Resonant soft X-ray emission (RSXE) spectra of V 2 O 3 , VO 2 and NaV 2 O 5 were recorded for a series of excitation energies at resonances of the V L- and O K-absorption band. The V L- and O K-emission in these vanadium oxide bands possess considerable overlap. By resonant excitation we can tune the energy to the absorption thresholds, thereby eliminating this overlap. Hereby we obtain the V 3d and O 2p projected density-of-states of the valence band. Resonant inelastic X-ray scattering (RIXS) is found to be weak in V 2 O 3 , which we explain as being due to its metallic character at room temperature. Vanadium dioxide ( VO 2 ), semiconducting at room temperature, shows considerable RIXS features only at the O K-emission band. Distinct RIXS structures are visible in the RSXE spectra of the insulator NaV 2 O 5 . In the emission spectra excited at the V L-thresholds of this ternary vanadium oxide, dd-excitations of the V d xy subband at an energy loss of -1.7 eV are observed. Our observation, that RIXS is stronger for insulators than for metals, should be taken advantage of for studying insulator-to-metal transitions in vanadium compounds in the future.

c-Axis infrared reflectivity of magnetically aligned YBa2Cu3O(7-δ) as a function of doping

Publisher: Springer Science and Business Media LLC

Date: 11-1996

DOI: 10.1007/BF00768477

P-f hybridization in the ferromagnetic semiconductor HoN

Publisher: AIP Publishing

Date: 13-02-2012

DOI: 10.1063/1.3687176

Abstract: The electronic structure of thin film HoN has been studied using soft x-ray spectroscopy. The combination of soft x-ray emission, x-ray absorption, and photoemission techniques yields direct evidence for hybridization between the N 2p and the Ho 4f states, previously unseen in this or related rare earth nitride systems. The N 2p states extend up to 10 eV below the Fermi level to nearly twice the binding energy as previously believed. Optical spectroscopy yields a minimum direct gap of 1.48 eV. In light of these results, we identify HoN as a prime candidate for spin-diffusion and spintronics applications.

Bandlike and excitonic states of oxygen inCuGeO

Publisher: American Physical Society (APS)

Date: 02-2000

DOI: 10.1103/PHYSREVB.61.4186

X-ray spectroscopic study of the electronic structure of the high-dielectric-constant material Ca Cu3 Ti4 O12

Publisher: American Physical Society (APS)

Date: 23-05-2005

DOI: 10.1103/PHYSREVB.71.195111

Characteristics of 2-photon ultraviolet laser etching of diamond

Publisher: The Optical Society

Date: 12-07-2011

DOI: 10.1364/OME.1.000576

Curved Gratings as Plasmonic Lenses for Linearly Polarised Light

Publisher: Springer Science and Business Media LLC

Date: 25-08-2015

DOI: 10.1007/S11468-015-0031-2

Carbon supported hybrid catalysts for controlled product selectivity in the hydrosilylation of alkynes

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D0CY02136A

Abstract: A series of Rh- and Ir-hybrid catalysts with varying tether lengths has been prepared by immobilization of Rh I , Rh III and Ir III complexes on carbon black, and applied in the hydrosilylation of alkynes.

Focusing surface plasmons by a plasmonic lens

Publisher: SPIE

Date: 10-09-2014

DOI: 10.1117/12.2060618

Comparison between experiment and calculated band structures for DyN and SmN

Publisher: American Physical Society (APS)

Date: 20-12-2007

DOI: 10.1103/PHYSREVB.76.245120

Graphene photo-detector enhanced by plasmonic coupling

Publisher: IEEE

Date: 07-2017

DOI: 10.1109/CLEOPR.2017.8118867

Thermoelectric power of the Fe(85 - x)(Cr, Ni)(x)B(15)series of glassy metals

Publisher: Elsevier BV

Date: 1998

DOI: 10.1016/S0304-8853(97)01050-0

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations

Publisher: AIP Publishing

Date: 10-12-2008

DOI: 10.1063/1.3030975

Abstract: The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq3) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq3, and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with in idual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

Magnetic structure of DyN: A Dy-161 Mossbauer study

Publisher: American Physical Society (APS)

Date: 27-02-2017

DOI: 10.1103/PHYSREVB.95.054431

Plasmonic second-harmonic generation in gold:lithium niobate thin films

Publisher: The Optical Society

Date: 17-01-2018

DOI: 10.1364/JOSAB.35.000302

Surface electronic structure of the organic superconductor κ-(ET)2Cu(NCS)2 studied via photoemission microscopy

Publisher: Elsevier BV

Date: 03-2004

DOI: 10.1016/J.SUSC.2003.12.050

Band-gap evolution, hybridization, and thermal stability of InxGa1-xN alloys measured by soft X-ray emission and absorption

Publisher: American Physical Society (APS)

Date: 24-04-2002

DOI: 10.1103/PHYSREVB.65.205201

Studies of the electronic structure in complex materials using synchrotron radiation‐excited soft x‐ray emission spectroscopy at the NSLS

Publisher: Informa UK Limited

Date: 05-2002

DOI: 10.1080/08940880208602951

Density of states, hybridization, and band-gap evolution inAl

Publisher: American Physical Society (APS)

Date: 15-07-1998

DOI: 10.1103/PHYSREVB.58.1928

Engineering regioselectivity in the hydrosilylation of alkynes using heterobimetallic dual-functional hybrid catalysts

Publisher: Royal Society of Chemistry (RSC)

Date: 2022

DOI: 10.1039/D1CY01804C

Abstract: The synthesis and characterization of carbon black supported rhodium and iridium heterobimetallic hybrid catalysts and their application in the hydrosilylation of alkynes is described.

Electronic structure of thin film silicon oxynitrides measured using soft x-ray emission and absorption

Publisher: AIP Publishing

Date: 29-08-2003

DOI: 10.1063/1.1599629

Abstract: The elementally resolved electronic structure of a thin film silicon oxynitride gate dielectric used in commercial device fabrication has been measured using soft x-ray emission and absorption spectroscopies. The SiOxNy was grown by annealing SiO2 in NH3. Soft x-ray emission and soft x-ray absorption were used to measure the valence and conduction band partial density of states in the interfacial region of both the nitrogen and oxygen states. The elementally specific band gap for the O 2p states was measured to be 8.8 eV in the interfacial region, similar to that of pure SiO2. The elementally specific band gap for the N 2p states in the interfacial region was measured to be approximately 5 eV.

Calorimetric evaluation of responses of Sitophilus oryzae and Tribolium confusum to elevated temperatures and controlled atmospheres

Publisher: Elsevier BV

Date: 2008

DOI: 10.1016/J.JSPR.2008.03.002

Electronic properties of (Ga,Mn)N thin films with high Mn content

Publisher: AIP Publishing

Date: 15-11-2008

DOI: 10.1063/1.3020536

Abstract: Optical and dc resistivity measurements as well as x-ray spectroscopies have been performed on (Ga,Mn)N films containing Mn at up to 11 at. %. The results indicate that at higher Mn contents, the Fermi level is situated within extended states, while GaN host interband optical transitions are unaffected. The Mn state is confirmed to be 3d5, as in the case of lower Mn content films however, the high Mn content merges the 3d levels into a band located just below the host conduction band. The Fermi level is located within these Mn states just below the conduction band, in sharp contrast to its midgap position in fully crystalline, low Mn concentration materials. The difference in the position of the Fermi level at high Mn dopant levels has important implications for the promotion of ferromagnetism in this material.

Observation of highly dispersive surface states on gan(0001)1×1

Publisher: American Physical Society (APS)

Date: 15-06-1999

DOI: 10.1103/PHYSREVB.59.R15586

Intrinsic reduction of the ordered4fmagnetic moments in semiconducting rare-e

Publisher: American Physical Society (APS)

Date: 26-02-2014

DOI: 10.1103/PHYSREVB.89.064424

Morphogenesis of mesoscopic surface patterns formed in polarized two-photon etching of diamond

Publisher: Elsevier BV

Date: 03-2021

DOI: 10.1016/J.CARBON.2020.09.029

Soft X-ray spectroscopy study of electronic structure in the organic semiconductor titanyl phthalocyanine (TiO-Pc)

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B717224A

Influence of shallow core-level hybridization on the electronic structure of post-transition-metal oxides studied using soft X-ray emission and absorption

Publisher: American Physical Society (APS)

Date: 20-10-2003

DOI: 10.1103/PHYSREVB.68.165104

Investigation of surface plasmon amplification in finite-width gold stripline based on Nd:YVO4 crystal

Publisher: OSA

Date: 2013

DOI: 10.1364/CLEO_QELS.2013.QTH4B.8

Effects of crystallinity and chemical variation on apparent band-gap shift in polycrystalline indium nitride

Publisher: Elsevier BV

Date: 2011

DOI: 10.1016/J.TSF.2010.10.013

Low activation energy for the removal of excess nitrogen in nitrogen rich indium nitride

Publisher: AIP Publishing

Date: 02-01-2012

DOI: 10.1063/1.3673839

Abstract: For some InN films large amounts of excess nitrogen are seen at low growth temperatures. Recent studies have revised downward the defect formation energies for several forms of nitrogen rich point-defects in InN. Here we calculate an activation energy of 0.4 ± 0.1 eV for the thermally activated removal of much of the excess nitrogen, believed to be interstitial nitrogen. This low energy barrier is shown to support the case for a low defect formation energy of the same native defect, although it is pointed out that non-equilibrium plasma based conditions are required to reach these lower defect formation energies.

Enhancement of UV laser induced etching of diamond under vacuum

Publisher: Optica Publishing Group

Date: 2020

DOI: 10.1364/CLEOPR.2020.C12A_2

Abstract: An investigation into UV two-photon etching of diamond surfaces in low pressure conditions is presented. A tenfold increase in etch rate was observed, attributed to the reduced role of water vapour in suppressing carbon ejection.

Macquarie University

Location: Australia

View Organisation

Linkage Projects - Grant ID: LP140100344

Start Date: 05-2015

End Date: 12-2020

Amount: $450,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0556391

Start Date: 2005

End Date: 12-2008

Amount: $368,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100235

Start Date: 05-2011

End Date: 12-2011

Amount: $180,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE200100033

Start Date: 2020

End Date: 03-2022

Amount: $1,200,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989567

Start Date: 03-2009

End Date: 09-2010

Amount: $500,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR120200004

Start Date: 07-2012

End Date: 12-2015

Amount: $30,000,000.00

Funder: Australian Research Council