Surface morphological and elemental imaging by low power atmospheric pulsed spark discharge optical emission spectrometry

A new surface morphological and elemental imaging system was built by using low power atmospheric pulsed spark discharge optical emission spectrometry (PSD-OES). This PSD-OES can well excite atomic lines of iron, chromium, zinc, copper and more. Optical emission intensity is affected by the distance between electrode and sample surface significantly when the electrode is very close to sample, enabling the surface morphological imaging possible for some samples such as a coin. For a roughly flat surface sample, when the distance is set at about 0.5 mm, the optical emission intensity is insensitive to tiny distance change, thus elemental imaging is possible. As an example, zinc stripes on copper plate can be well recognized by this elemental imaging technique, with a spatial resolution about tens of micrometers, which can be further improved by minimizing the optical aperture. A significant advantage of this technique is that it can obtain information at a series of specific wavelengths from a signal experiment for multi-element imaging.