Absolute Intensities of the Discrete and Continuous Absorption Bands of Oxygen Gas at 1.26 and 1.065 μ and the Radiative Lifetime of the 1Δg State of Oxygen

Abstract

Laboratory measurements have been made of the absolute intensities of the discrete-line absorption band at 1.26 μ, and of the continuous bands at 1.26 and 1.065 μ in oxygen gas at pressures up to 4.3 atm. It has been shown that discrete and continuous absorptions are quite independent features, the one being a measure of the intrinsic transition probability in isolated molecules, the other of its enhancement in collision complexes. In the former the lines show significant pressure broadening, but the integral molecular absorption coefficients are constant; in the latter they are proportional to pressure and continuous absorption dominates in the 1.26-μ region at about ½ atm oxygen pressure. The radiative half-life of isolated 1Δg oxygen molecules is estimated to be 45 min, and the effect of gas pressure on the rate of decay has been predicted.

Rocket Observation of Twilight Airglow in the Near Infrared Region

“…Both the spontaneous emission and the collisional quenching are responsible for the decay. The mean lifetime for the former is (BADGER et al 1965) r2=6510min.…”

Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78° N, 16° E)

“…The OH-B wavelength range, 1.56-1.72 µm, includes the O 2 Infrared Atmospheric (0,1) emission at 1.58 µm, which has a lifetime of ∼3900 s (Badger et al, 1965). This very long lifetime for an airglow species results in a significant fraction of twilight and early nightglow arising from remnant dayglow excitation, which could contaminate the OH-B VER.…”

“…The OH-B band channel is sensitive in the range 1.56-1.72 µm which includes mostly the OH(4-2) and OH(5-3) bands and was selected in preference to the OH-A channel, which includes mostly the v=2 bands originating in levels 9 and 8, because the higher vibrational bands tend to have their maxima at higher altitude (Kaufmann et al, 2008). Baker et al (2007) made use of this channel in their study of equatorial enhancements of the nighttime mesospheric OH airglow layer.…”

Measurement of mesospheric ozone concentrations from the 1.27.MU.m O2 airglow at a middle latitude.

“…The transition probability is given as A00=2.6x 10-sec-1 for the (0,0) band (BADGER et al, 1965), and A01=3.5x10-6sec-1 for the (0,1) band (HASLETT and FEHSENFELD, 1969). Thus the total transition probability for v'=0 of the 149 state if A=Aoi-Aoo.…”