Two-dimensional Observation of Emission Image of a Copper Chip Excited in a Glow Discharge Plasma

概要

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A two-dimensionally imaging spectrometer system was employed to obtain an emission image of a test specimen and to estimate the lateral resolution, when it was excited from a glow discharge plasma at a pulsed direct-current voltage. The specimen was a square-shaped copper chip having a dimension of 1.0 × 1.0 mm stuck on a nickel substrate. A Grimm-style glow discharge excitation source, whose hollow anode had an inner diameter of 8 mm, was employed as the excitation source. A conventional discharge condition did not give good lateral resolution being suitable for the actual application, because the emitting zone extended broadly over the size of the copper chip. The gate width of the charge-coupled device (CCD) detector and the on/off-periods of the discharge were investigated to improve the lateral resolution. Degradation of the resolution would be caused by the fact that a sample atom emits at different portions of the plasma body repeatedly, even during a single pulse of the discharge. Therefore, it is suggested that the gate width of the CCD detector should be reduced as small as possible, so that the emission of a sample atom can be detected instantaneously after ejected from the original position in the sample surface.