With the use of charge coupled device observation technology, single spark data have shown a limitation of current sample introduction models for the high-voltage atmospheric pressure spark. Two-dimensional spatial Images of wavelength-resolved data show that atomic emission varies not only in position but also in amplitude. Vapor jets are not observed, but rather nebulous clouds of emission, greatly varying in intensity, are seen.
Brian J. Mork and Alexander Scheeline, "Wavelength-Resolved Single-Spark Emission Images with the Use of a Charge Coupled Device Detector," Appl. Spectrosc. 42, 1332-1335 (1988)