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

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

FURTHER STUDIES OF GROUP HA VAN DER WAALS DIATOMIC MOLECULES

$^{1}$W. J. Balfour and A. E. Douglas, Can. J. Phys. 48, 901 (1970).""Author Institution: Department of Chemistry, University of VictoriaThe absorption spectrum of calcium vapor has been studied at 2300 K using a King furnance. With increasing temperature the 4227 \AA resonance line of atomic Ca broadens markedly to the red and under high resolution the region from 4600 \AA to 6000 \AA shows a complex many-line spectrum. Rotational analysis confirms the spectrum as due to a $^{1}\Sigma$ --- $^{1}\Sigma$ transition of diatomic calcium. The situation is analogous to that already observed for $magnesium,^{1}$ where the transition is from a very lightly bonded ground state to a more stable excited state. The rotational and vibrational structure of the $Ca_{2}$ spectrum will be discussed, and calculations of the Franck-Condon effect in the $Mg_{2}$ spectrum will be reported