Closed Field Unbalanced Magnetron Sputtering Ion Plating (CFUBMSIP) has been used to deposit undoped and nitrogen doped NiAI thin films onto glass and stainless steel 316 substrates. These films have potential applications in tribological, electronic media and thermal barrier coatings. The surface characteristics, composition, mechanical and structural properties have been investigated using stylus profilometry, X-ray diffraction (XRD), Energy dispersive spectroscopy (EDAX), Atomic force microscopy (AFM) and nanoindentation. The average thickness of the films was approximately 1 microm. The X-ray diffraction spectra revealed the presence of the beta NiAl phase. The EDAX results revealed that all of the undoped and nitrogen doped NiAl thin films exhibited the near equiatomic NiAl composition with the best results being achieved using 300 Watts DC power for Ni and 400 Watts DC power for Al targets respectively. AFM results of both types of films deposited on glass samples exhibited a surface roughness of less than 100 nm. The nanoindenter results for coatings on glass substrates displayed hardness and elastic modulus of 7.7 GPa and 100 GPa respectively. The hardest coatings obtained were obtained at 10% of nitrogen.

Different correlations were used to predict monthly average global and diffuse radiation on a horizontal surface at Tripoli. The estimated results are then compared with the experimental data for the year 1989-1990. Using statistical tests the RMSE, MBE and MABE to evaluate these correlations, it was found that the Dogeniaux-Lemoin, and the Erbs-Klein and Duffie correlations are the best to predict the global and the diffuse radiation respectively. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

This paper presents the general features of the global solar radiation measured by 15 meteorological stations spread over Libya during the 5-yr period, 1981–1986. A number of methods for correlating monthly average daily global radiation with recorded sunshine duration have been attempted. It is found that some well known correlation formulae show large discrepancies in predicting the global radiation of Libya. However, the Dogniaux-Lemoine correlation equation is found to be suitable for the prediction, particularly in the coastal regions. The present analysis indicates that solar radiation in the Libyan climate can be classified into two broad divisions, coastal and desert, with two sub-divisions in each of the divisions. Station-independent correlation parameters for these regions are calculated.

A comparison of VUV absorption with near-threshold electron energy-loss spectra, has led to the identification of several new low-lying electronic states of pyridazine. The assignment of these and previously known singlet states is discussed in the light of large-scale all-valence electron CI calculations using a multi-reference, multi-root CI (MRDCI) study, which includes Rydberg orbitals in the basis set. The UV-photoelectron spectrum is reconsidered in the light of these calculations and it is concluded that IP2 is of 2B1 rather than 2A2 symmetry. The ground state molecular electronic properties are evaluated with a large SCF/CI basis, and compared with available experimental data.

New low-energy electron scattering and vacuum UV absorption spectra for cis- and trans-but-2-enes have been interpreted by ab initio configuration interaction calculations, to yield a consistent interpretation of the order of singlet and triplet excited states in the 6–10 eV range. The UV-photoelectron spectra have been similarly re-interpreted by CI calculations. A large number of shake-up states are obtained; the computed differences in energy between pairs of such states with two common open shells lead to remarkably good values for the T and V state energies of the ground state molecule.

VUV (6.2–9 eV) and electron scattering spectra (1–9 eV) have been recorded for 2-methylpropene (isobutene). Also, electronic states of the molecule, including the ground state and cationic states, have been investigated using ab initio multi-reference configuration interaction calculations. Some Koopmans-type in the UV photoelectron spectrum are reassigned and a number of shake-up states computed. In the electronic spectrum, Rydberg excited have been assigned and a second valence excited state (σ π*) located within about 1 eV of the V(ππ*) state. The experiments show, and theory confirms, that the Rydberg R(π3s) state has a positive electron affinity. Some interesting correlations between ionisation energies, energies of shake-up state electronic excitation energies are identified.

Electronic excitation of H2S by impact with near-threshold-energy electrons has been studied. Comparison of the electron scattering data with optical spectra has led to the location of a number of optically forbidden electronic states. Of these, states at ca. 5.4 and 5.8 eV excitation energy are assigned as the lowest-lying triplet states 3B1 and 3A2′, respectively. A broad energy-loss band at ca. 7.4 eV is assigned to a valence-excited state of 1A2 symmetry, while structure at 8.55 eV is ascribed to excitation of a Rydberg 1A2 state.

The electronic states of ethylene in the range 0–10 eV have been reassessed in the light of new electron scattering data for C2H4 and C2D4 and ab initio multi-reference configuration interaction and iterative natural orbital calculations with large basis sets. Existing assignments for many low-lying singlet and triplet states are substantiated and a number of new states have been computed. With the exception of the V (1B1u) state which is ππ* and states 21B1g and 21B2g (both σπ*) all of the singlet states in this energy range are of Rydberg character. The role of a resonant intermediate, the 2B3u anion, in electron scattering from ethylene is confirmed theoretically.

The near-threshold excitation of sulphur dioxide has been studied using a trapped-electron spectrometer. The results suggest that excitation energies for the three low-lying triplet electronic energy states, 3B1, 3B2 and 3A2, all lie within the range 3.1–3.9 eV and that two other triplet states are excited at ca. 7.75 and 8.4 eV electron energy loss.

Near-threshold electron-impact excitation of ammonia and methylamine have been explored in a trapped-electron spectrometer. The lowest triplet state in each molecule lies ca. 0.4 eV below the singlet à state, consistent with the accepted Rydberg description of the à state.