Aims. We report on the production of a large area, shallow, sky survey, from XMM-Newton slews. The great collecting area of the mirrors coupled with the high quantum efficiency of the EPIC detectors have made XMM-Newton the most sensitive X-ray observatory flown to date. We use data taken with the EPIC-pn camera during slewing manoeuvres to perform an X-ray survey of the sky. Methods. Data from 218 slews have been subdivided into small images and source searched. This has been done in three distinct energy bands; a soft (0.2-2 keV) band, a hard (2-12 keV) band and a total XMM-Newton band (0.2-12 keV). Detected sources, have been quality controlled to remove artifacts and a catalogue has been drawn from the remaining sources. Results. A "full" catalogue, containing 4710 detections and a "clean" catalogue containing 2692 sources have been produced, from 14% of the sky. In the hard X-ray band (2-12 keV) 257 sources are detected in the clean catalogue to a flux limit of 4 × 10 −12 ergs s −1 cm −2 . The flux limit for the soft (0.2-2 keV) band is 6 × 10 −13 ergs s −1 cm −2 and for the total (0.2-12 keV) band is 1.2 × 10 −12 ergs s −1 cm −2 . The source positions are shown to have an uncertainty of 8 (1σ confidence).

In this work we present a theoretical and experimental study of the acetylene -hydrogen system.A potential surface considering rigid monomers has been obtained by ab initio quantum chemistry methods. This 4-dimensional potential is further employed to compute using the close-clouping approach and the coupled-states approximation pressure broadening coefficients of C 2 H 2 isotropic Raman Q lines over a temperature range of 77 to 2000 K. Experimental data for the acetylene ν 2 Raman lines broadened by molecular hydrogen are obtained using stimulated Raman spectroscopy.The comparison at 143 K of theoretical values with experimental data is promising. Approximations to increase computational efficiency are proposed. *

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Line-mixing effects have been studied in the 3 band of CH 4 perturbed by N 2 at room temperature. New measurements have been made and a model is proposed which is not, for the first time, strictly empirical. Three different experimental set ups have been used in order to measure absorption in the 2800-3200 cm Ϫ1 spectral region for total pressures in the 0.25-2 and 25-80 atm ranges. Analysis of the spectra demonstrates the significant influence of line mixing on the shape of the Q branch and of the P and R manifolds. A model is proposed which is based on state-to-state collisional transfer rates calculated from the intermolecular potential surface with a semiclassical approach. The line-coupling relaxation matrix is constructed from these data and two additional parameters which are fitted on measured absorption. Comparisons between measurements and spectra computed accounting for and neglecting line mixing are made. They prove the quality of the approach which satisfactory accounts for the effects of pressure and of rotational quantum numbers on the spectral shape under conditions where modifications introduced by line mixing are important. For high rotational quantum number lines, the main features induced by collisions are predicted but some discrepancies remain; the latter may be due to improper line-coupling elements but there is strong evidence that the use of inaccurate line broadening parameters also contributes to errors in calculated spectra.

We present measurements of Raman linewidths in the fundamental Q branch of CO for mixtures with Ar at temperatures of 77, 195, and 300 K, recorded using an inverse Raman spectrometer. Starting from a recent ab initio potential energy surface, theoretical values of Ar broadening coefficients for CO infrared and Raman lines (isotropic and anisotropic components) at temperatures in the range 77 to 1100 K are calculated via quantum-mechanical methods. The relative merits of the close coupling theoretical results over the coupled states results are underlined. Finally, a comparison of the calculated pressure broadening coefficients is made with the present experimental data as well as with recently available infrared data. There is general agreement between the calculated and measured values of the broadenings for all the temperatures probed. We conclude that the temperature dependence of the infrared and Raman broadening coefficients have been correctly determined theoretically and may be used to test a common temperature scaling law.