“…Previous attempts to detect O( 1 S) by techniques such as Auger emission from a low work function surface (Alcock and McConkey, 1978;Gilpin and Welge, 1971), by a chemi-ionization process (Stone et al, 1976), or by detection of inelastically scattered electrons, were limited by a lack of sensitivity or suffered from poor discrimination against other metastable atomic or molecular species, such as O( 5 S), or ground state O( 3 P), and generally suffered from poor signal to background ratios. Optical methods to record emissions from the low lying oxygen metastables relied on buffering the metastable atoms from the walls using rare gases such as He, as used by McLennan and Shrum (1925) in their historic experiment or by lifetime shortening through excimer formation with high pressure Kr or Xe gases (Cooper et al, 1961;Cunningham and Clark, 1974;Herman and Herman, 1950;Huestis et al, 1975;Kenty et al, 1946;Simmons et al, 1979).…”