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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

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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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Abstract

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.