Excitation of VUV Atomic Sulphur Emissions following Electron-Sulphur Interactions

A beam of sulphur, obtained by evaporation of solid sulphur, was crossed by an electron beam of carefully controlled energy and the resulting VUV radiation was detected, in a direction perpendicular to both beams, by a $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ meter Seya-Namioka monochromator with a CsI-coated channel electron multiplier detector. In an associated experiment a microwave discharge was used to dissociate the sulphur molecules released during evaporation. Relative calibration of the detection sensitivity over the wavelength range 90-170 nm was achieved using the well known spectrum of H$_{2}$ in this spectral region. Data, covering the electron-impact energy range from threshold to 350 eV, on the planetary-important multiplets at 142.5, 147.4 and 167.7 nm will be presented together with a full description of the experimental techniques, possible fragmentation channels etc.