A new short-wavelength carbon dioxide band in the spectrum of Venus

Extract

In attempting to resolve the CO₂ band at 7159 Å identified in the spectrum of Venus by Spinrad (1962), we discovered a new band at 7105 Å. Both bands are fully resolved on our spectra and tentative J numbers have been assigned to the rotational lines. In both cases, the P branch appears to be anomalously weak. The 7159 Å band has been observed in the laboratory (unresolved) by Herzberg and Herzberg (1953) at path lengths on the order of 55 km atm. To our knowledge, the 7105 Å band has not been recorded previously. Following the predictions of Herman (1948) the two bands are given the assignments 5v₃ + 2v₂ + v₁ (7159 Å) and 5v₃ + 2v₁ (7105 Å). An unsuccessful attempt was made to find the third member of this triad, 5v₃ + 4v₂. In view of the very large amount of carbon dioxide apparently required to produce these absorptions, further study in the laboratory and at the telescope is encouraged.