Evaluation of X-ray/EUV Nanolithography Facility at AS Through Wavefront Propagation Simulations

Synchrotron light sources can provide the required spatial coherence, stability and control that is required to support the development of advanced lithography at the extreme ultraviolet and soft X-ray wavelengths that are relevant to current and future fabricating technologies. Here we present an evaluation of the optical performance of the soft X-ray (SXR) beamline of the Australian Synchrotron (AS) and its suitability for developing interference lithography using radiation in the 91.8 eV (13.5 nm) to 300 eV (4.13 nm) range. A comprehensive physical optics model of the APPLE-II undulator source and SXR beamline was constructed to simulate the properties of the illumination at the proposed location of a photomask, as a function of photon energy, collimation, and monochromator parameters. The model is validated using a combination of experimental measurements of the photon intensity distribution of the undulator harmonics. We show that the undulator harmonics intensity ratio can be accurately measured using an imaging detector and controlled using beamline optics. Finally, we evaluate photomask geometric constraints and achievable performance for the limiting case of fully spatially coherent illumination.Comment: 21 pages, 7 figures, 3 tables. Preprint: submitted to Journal of Synchrotron Radiation 16/11/2

Probing the effect of metal to ligand charge transfer on the oxygen evolution reaction in Au incorporated Co(OH)2 thin film electrocatalysts

First row transition metal oxides have shown potential as affordable catalysts for the oxygen evolution reaction (OER). The addition of small amounts of noble metals such as gold offers significant improvements in catalytic activity while maintaining affordability. However, a fundamental understanding of this enhancement in catalytic activity is still lacking. In this work we correlate Near Edge X-ray Absorption Fine Structure (NEXAFS) data to conventional characterisation techniques to analyse the oxidation state changes that occur during the OER in cobalt oxide and cobalt oxide-gold based electrocatalyst thin films to understand their effect on the reaction. We find that the incorporation of gold into the cobalt oxide significantly reduces the ligand to metal charge transfer process on the catalyst surface. We propose that the reduced ligand to metal charge transfer facilitates the formation of the key M-OOH* intermediate (where M is the metal and -OOH* is the ligand) and desorption of O2 from the catalyst surface, leading to an overall increase in catalyst performance. This study sheds light on how incorporation of a small amount of highly electronegative noble metal may have the scope to significantly improve the reactivity of transition metal based thin film catalysts for OER by optimising the ligand to metal charge transfer effect.</p

Probing the effect of metal to ligand charge transfer on the oxygen evolution reaction in Au incorporated Co(OH)2_2 thin film electrocatalysts

First row transition metal oxides have shown potential as affordable catalysts for the oxygen evolution reaction (OER). The addition of small amounts of noble metals such as gold offers significant improvements in catalytic activity while maintaining affordability. However, a fundamental understanding of this enhancement in catalytic activity is still lacking. In this work we correlate Near Edge X-ray Absorption Fine Structure (NEXAFS) data to conventional characterisation techniques to analyse the oxidation state changes that occur during the OER in cobalt oxide and cobalt oxide-gold based electrocatalyst thin films to understand their effect on the reaction. We find that the incorporation of gold into the cobalt oxide significantly reduces the ligand to metal charge transfer process on the catalyst surface. We propose that the reduced ligand to metal charge transfer facilitates the formation of the key M–OOH* intermediate (where M is the metal and –OOH* is the ligand) and desorption of O2 from the catalyst surface, leading to an overall increase in catalyst performance. This study sheds light on how incorporation of a small amount of highly electronegative noble metal may have the scope to significantly improve the reactivity of transition metal based thin film catalysts for OER by optimising the ligand to metal charge transfer effect

Evaluation of the X-ray/EUV Nanolithography Facility at AS through wavefront propagation simulations

Synchrotron light sources can provide the required spatial coherence, stability and control to support the development of advanced lithography at the extreme ultraviolet and soft X-ray wavelengths that are relevant to current and future fabricating technologies. Here an evaluation of the optical performance of the soft X-ray (SXR) beamline of the Australian Synchrotron (AS) and its suitability for developing interference lithography using radiation in the 91.8 eV (13.5 nm) to 300 eV (4.13 nm) range are presented. A comprehensive physical optics model of the APPLE-II undulator source and SXR beamline was constructed to simulate the properties of the illumination at the proposed location of a photomask, as a function of photon energy, collimation and monochromator parameters. The model is validated using a combination of experimental measurements of the photon intensity distribution of the undulator harmonics. It is shown that the undulator harmonics intensity ratio can be accurately measured using an imaging detector and controlled using beamline optics. Finally, the photomask geometric constraints and achievable performance for the limiting case of fully spatially coherent illumination are evaluated

Monitoring dynamic electrochemical processes with in situ ptychography

he present work reports novel soft X-ray Fresnel CDI ptychography results, demonstrating the potential of this method for dynamic in situ studies. Specifically, in situ ptychography experiments explored the electrochemical fabrication of Co-doped Mn-oxide/polypyrrole nanocomposites for sustainable and cost-effective fuel-cell air-electrodes. Oxygen-reduction catalysts based on Mn-oxides exhibit relatively high activity, but poor durability: doping with Co has been shown to improve both reduction rate and stability

Phase-diverse Fresnel coherent diffractive imaging of malaria parasite-infected red blood cells in the water window

Phase-diverse X-ray coherent diffractive imaging (CDI) provides a route to high sensitivity and spatial resolution with moderate radiation dose. It also provides a robust solution to the well-known phase-problem, making on-line image reconstruction feasible. Here we apply phase-diverse CDI to a cellular sample, obtaining images of an erythrocyte infected by the sexual stage of the malaria parasite, Plasmodium falciparum, with a radiation dose significantly lower than the lowest dose previously reported for cellular imaging using CDI. The high sensitivity and resolution allow key biological features to be identified within intact cells, providing complementary information to optical and electron microscopy. This high throughput method could be used for fast tomographic imaging, or to generate multiple replicates in two-dimensions of hydrated biological systems without freezing or fixing. This work demonstrates that phase-diverse CDI is a valuable complementary imaging method for the biological sciences and ready for immediate application

Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline

Free to read\ud \ud Owing to its extreme sensitivity, quantitative mapping of elemental distributions via X-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated