Synchrotron x-ray radiation is being used extensively as a structure probe to investigate the coordination environment and thus gain insight into the ion–water and ion–ion interactions in aqueous solutions. However, under favorable conditions, there may be instances where the incident x-ray beam can induce oxidation and/or reduction in the solution, thus altering its chemistry. Successive x-ray absorption fine structure spectra, measured in the fluorescence mode from a 55 ppm Cu in CuCl2 aqueous solution, show the formation of copper clusters and their growth as a function of time of irradiation. Initially, the clusters have a nearest neighbor distance of 2.48±0.02 Å which, with increase in time of irradiation, increases to 2.55±0.01 Å, indicating that the clusters approach the lattice dimensions of bulk copper. Similarly, the Debye–Waller factor of the copper clusters is found to increase by ∼50%–55% over the range of time of irradiation. Analysis of spectra measured in the intermediate time period shows signal contributions from a mixture of clusters that can be represented by a mixture of a small cluster (5–10 Å across) and bulk copper. The nearest neighbor coordination number is found to increase in a manner consistent with the decrease in the surface to volume ratio as the average cluster size approaches its bulk dimensions. The initiation of cluster growth occurs through agglomeration of copper atoms that possibly react to form dimers upon reaction. The copper ions in the solution are reduced to the metallic state by reacting with hydrated electrons produced as a result of radiolysis of water by the incident x-ray beam.

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We report here on X-ray absorption fine structure (XAFS) measurements used to determine the structure of the Yb 3+ ion in aqueous solutions over a range of temperatures from 25 to 500 °C and pressures up to 270 MPa. Fluorescence Yb L 3 -edge spectra were collected separately from nitrate (0.006m Yb/0.16m HNO 3 ) and chloride (0.006 m YbCl 3 /0.017 m HCl) aqueous solutions within a hydrothermal diamond anvil cell. The Yb-O distance of the Yb 3+ aquo ion in the nitrate solution exhibits a uniform reduction at a rate of 0.02 Å/100 °C, whereas the number of oxygens decreases from 8.3 ( 0.6 to 4.8 ( 0.7, in going from 25 to 500 °C. No evidence for nitrate complexes was found from measurements made on this solution. The Yb 3+ is found to persist as an aquo ion up to 150 °C in the chloride aqueous solution. In the 300-500 °C range, chloro complexes are found to occur in the solution, most likely of the type Yb(H 2 O) δ-n Cl n +3-n (δ ≈ 7). The Yb-Cl distance of the chloro ytterbium(III) complexes is found to decrease uniformly at a rate of about 0.02 Å/100 °C, whereas the number of chlorines increases from 0.5 ( 0.3 to 1.8 ( 0.2 in the 300-500 °C temperature range. Conversely, the Yb-O distance undergoes a lower uniform reduction at a rate of 0.007 Å/100 °C, whereas the number of oxygens decreases from 8.3 ( 0.5 to 5.1 ( 0.3 in going from 25 to 500 °C in the same solution.

We report electrodeposition of n-type cuprous oxide (Cu 2 O) films on p-type CuO films electrodeposited on Ti substrates for forming p-CuO/n-Cu 2 O heterostructures. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed that the films had good structural quality, with substrates being well-covered by the films. The p-CuO/n-Cu 2 O heterojunctions exhibited good photovoltaic properties and diode characteristics. The surfaces of Cu 2 O films subject to ammonium sulfide treatment exhibited enhanced photocurrents. Under AM 1.5 illumniation, the obtained sulfur-treated and annealed Ti/p-CuO/n-Cu 2 O/Au solar cell structure yielded energy conversion efficiency of 0.64%, with V oc = 220 mV and J sc = 6.8 mA cm %2 .

As one of the most widely used domestic fuels, the detection of possible leakages of Liquefied Petroleum (LP) gas from production plants, from cylinders during their storage, transport and usage is of utmost importance. This article discusses a study of the response of undoped and chlorine doped electrodeposited n-type Cuprous Oxide (Cu 2 O) films to of LP gas. Undoped n-type Cu 2 O films were fabricated in an electrolyte bath containing a solution of sodium acetate and cupric acetate whereas n-type chlorine doped Cu 2 O thin films were prepared by adding a 0.02 M cuprous chloride (CuCl 2) into an electrolyte solution containing lactic acid, cupric sulfate and sodium hydroxide. The n-type conductivity of the deposited films was determined using spectral response measurements. The structural and morphological properties of the fabricated films were monitored using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Due to doping, the overall conductivity of the chlorine doped n-type Cu 2 O films increased by several orders of magnitude. The temperature dependent gas responses of both the undoped and chlorine doped n-type Cu 2 O thin films to the LP gas was monitored by measuring the electrical resistance (R), and using the contact probe method at a constant gas flow rate of 0.005 ml/s. Upon exposure to gases, both doped and undoped films showed a good response to the gas by increasing/decreasing the electrical resistance by ΔR. The undoped n-type Cu 2 O thin films showed a negative response (ΔR < 0) at all temperatures resulting in a maximum response around 85˚C. However, the chlorine doped n-type Cu 2 O thin films initially showed a positive response (ΔR > 0) to the LP gas which then reversed its sign to give a negative response which peaked at 52˚C. The positive response shown by the chlorine doped Cu 2 O films vanished completely at 42˚C. N. Bandara et al.