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In-plane total differential scattering cross sections for H2 scattered from N2 and HF are reported. The data are analyzed in terms of spherical and anisotropic potentials using single channel and IOS methods for calculating the differential cross sections. In the case of H2/HF the diffraction oscillations are highly damped at small angles, suggesting that the anisotropy is large. [ABSTRACT FROM AUTHOR]

A molecular beam apparatus has been used to study resonant rotational energy transfer between HF molecules in the ground vibrational state. A low temperature beam formed from the supersonic expansion of a gas mixture containing 1% HF in helium is attenuated by HF molecules with a thermal energy distribution. State selection of the molecular beam is accomplished by using an F-center laser in conjunction with a bolometer detector. The attenuation measurements show effects which are attributed to resonant rotational energy transfer. The results have been analyzed using a kinetic model to estimate the relevant cross sections. The first order dipole allowed process HF(J=0)+HF(J=1) →HF(J=1)+HF(J=0) is found to have a cross section of ∼300 Å2. The results also suggest that the second order cross sections, having ΔJ=2, are about 40 Å2. [ABSTRACT FROM AUTHOR]

Infrared spectra have been obtained for dimers formed from acetylene, methyl acetylene, and ethylene using a wide variety of free jet source conditions. An F-center laser was used to excite various C–H stretch fundamentals in the range 3000–3300 cm-1. Rotational structure was resolved in the spectra of both acetylene and methyl acetylene dimers when dilute mixtures of either gas in helium were expanded from high pressures. The spectrum of the ethylene dimer showed no such structure even when formed in very dilute mixtures. These results contradict previous suggestions that the vibrational relaxation lifetime is uniformly short for all polyatomic dimers. [ABSTRACT FROM AUTHOR]

Earth System Models (ESMs) that incorporate carbon-climate feedbacks represent the present state of the art in climate modelling. Here, we describe the Australian Community Climate and Earth System Simulator (ACCESS)-ESM1 that combines existing ocean and land carbon models into the physical climate model to simulate exchanges of carbon between the land, atmosphere and ocean. The land carbon model can optionally include both nitrogen and phosphorous limitation on the land carbon uptake. The ocean carbon model simulates the evolution of nitrate, oxygen, dissolved inorganic carbon, alkalinity and iron with one class of phytoplankton and zooplankton. From two multi-centennial simulations of the pre-industrial period with different land carbon model configurations, we evaluate the equilibration of the carbon cycle and present the spatial and temporal variability in key carbon exchanges. For the land carbon cycle, leaf area index is simulated reasonably, and seasonal carbon exchange is well represented. Interannual variations of land carbon exchange are relatively large, driven by variability in precipitation and temperature. We find that the response of the ocean carbon cycle shows reasonable agreement with observations and very good agreement with existing Coupled Model Intercomparison Project (CMIP5) models. While our model over estimates surface nitrate values, the primary productivity agrees well with observations. Our analysis highlights some deficiencies inherent in the carbon models and where the carbon simulation is negatively impacted by known biases in the underlying physical model. We conclude the study with a brief discussion of key developments required to further improve the realism of our model simulation. [ABSTRACT FROM AUTHOR]

Thermally oxidized TiO2 (rutile) films on titanium showed about an order of magnitude higher photoelectrochemical energy conversion efficiency for water splitting (∼0.2%, simulated AM 1.5 sunlight) when the substrate had been etched in acid prior to oxidation. We investigated the cause of the improved photocurrents. Film morphology is insufficient to explain the variation in photoelectrochemical response. Charge-carrier profiles from capacitance-voltage measurements using Schottky contacts indicated a gradual transition from near-stoichiometric oxide at the surface to highly substoichiometric deeper in the film approaching the titanium substrate for oxide grown on etched substrates. In contrast, the oxide layer on unetched samples showed higher carrier densities and a more abrupt transition to substoichiometric or metallic. This interpretation is supported by varying incidence-angle X-ray diffraction measurements suggesting more fully oxidized surface regions with a more gradual transition to suboxides for etched samples. Impedance measurements also suggested that the surface region of oxide layers grown on acid-etched substrates have fewer short-time-constant electronic defects (intraband gap states) than the surface of layers grown on more disordered metallic substrates. The improved photoelectrochemical performance probably results from higher charge-carrier mobilities, reduced recombination, and higher photoconductivity due to long time constants of trapping states. [ABSTRACT FROM AUTHOR]