Development of experimental gas electron diffraction technique

Abstract

A state-of-the-art gas electron diffraction (GED) apparatus has been reassembled in the school of chemistry at the University of Edinburgh. This combines molecularbeam and telefocus-electron-gun technologies and the alignment of the electron beam produced by the latter has been discussed. A new custom-made CCD detector has also been installed and electron diffraction patterns for a few small molecules have been recorded. In analogy to the rotating sector in a conventional GED apparatus, the new camera contains an optical filter and a procedure for its calibration is outlined and followed step by step to produce an estimate of the filter transmittance. The data have been shown to be of less than ideal quality and the probable root of the problem is discussed. GED refinements of two pairs of compounds (arachno-6,9-decaboranes, and a covalent sulfonate and thiosulfonate) are presented, using data collected with the conventional Edinburgh GED apparatus.