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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including those from the School of Psychological Sciences & Health - but also papers by researchers based within the Faculties of Science, Engineering, Humanities & Social Sciences, and from the Strathclyde Business School.

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Identification of the origins of photoionisation in CO2 tea lasers

Scott, S.J. and Smith, A.L.S. (1984) Identification of the origins of photoionisation in CO2 tea lasers. Applied Physics B - Photophysics and Laser Chemistry, 33 (1). pp. 1-5. ISSN 0721-7269

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In sealed CO2 spark preionized lasers, the preionization is largely due to photoionization of NO and NO2; in seeded TEA lasers it originates from the low ionization potential additive used. Unseeded and flowing gas lasers can still be successfully preionized but the source of this preionization has remained a mystery; previous attempts to isolate and identify low I.P. gaseous impurities have failed. These have now been identified, using a combination of cryogenic impurity concentration and mass spectroscopy and found to be a complex mixture of hydrocarbons (C2-C7). Of these hydrocarbons, the alkenes are found to be predominantly responsible for the photoionization and are present in concentrations of about 0.5 ppm. Deliberate addition of one of these alkenes, propene, to a UV preionized CO2 TEA laser was found to enhance the lasers performance at high energy loadings.