Altitude profiles of the 5577-A and 6300-A O I nightglow radiations have been observed with rocket photometers to an altitude of 258 km. Five hours after sunset, the 6300-A red line exhibited an intensity maximum at approximately 245 km. The 5577-A green line also exhibited a second intensity maximum at this same altitude in addition to the lower peak at 97 km. The high-altitude green line intensity was about % that of the red line intensity at the same altitude and about 1/10 that of the 5577-A layer at 97 km. The dissociative recombination reaction of O• + is the only mechanism required to explain the observed profiles. Upper limits for the specific dissociative recombination coefficients of O(XS) • 1.1 X 10 -s cm 8 sec -x and O(XD) • 3.5 X 10 -s cm • sec -x have been derived from these nightglow observations. An upper limit of • I X 10 -• c m8 see -x is obtained for the collisional deactivation coefficient of O(XD) with the assumption that molecular nitrogen is the principal deactivating species in the upper atmosphere. lNTRODUCTIOl• Many attempts have been made to determine the altitude from which atomic oxygen radiates the 6300-A line that is prominent in night airglow spectrograms. Measurements from the ground were generally unsuccessful until 1959 when Barbier [1959] developed a time-history technique for deriving the height at twilight. He placed the red line layer in the F region of the ionosphere between 200 and 300 km. Bates [1946] had postulated that this was the region of red line origin as early as 1946 and had suggested that dissociative recombinati.on of ions and electrons could be the source of such radiation. Chamberlain [1958] in a more detailed analysis of the oxygen red lines in the airglow, showed that dissociative recombination was the most probable source of the red nightglow and that the altitude of the emission layer should be in the neighborhood of 250-300 km. Dissociative recombination of O•* and electrons was also postulated by Nicolet [1954] to explain the total 5577-A radiation before the height of the 9T km layer had been accurately measured. tropical red arcs near the equator describ.ed by Barbier and Glaume [1960] also have placed this emitting region between 200 and 300 km. Rocket measurements by NRL as early as 1956 [Heppner and Meredith, 1958] indicated that the red line emission layer was above 163 km, and Zip) • and Heath [1962] reported that the emission was above 208 km. The theory of the dissociative recombination mechanism to produce the red line emission has been further developed by numerous workers [Lagos et al., 1963; Peterson et al., 1966; Holmes et al., 1965; Zip) •, 1966; Wallace and McElroy, 1966; Ferguson et al., 1965; and Swider, 1965]. Peterson and Van Zandt [1966] have also extended this theory to a weaker green line contribution above the 97-km layer in high-altitude tropical arcs. The first reported direct measurement, Gulledge and Packer [1965], of the nighttime red line altitude intensity distribution was made by NRL from a Javelin rocket, NASA 8.31 DA, l...
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