The vapors issuing from mullite and graphite Knudsen cells containing pure metals and alloys of the triad Cu–Ag–Au have been analyzed mass spectrometrically. From the experimental ratios of diatomic to monoatomic species and the vapor pressures of the elements, the following dissociation energies are obtained: D00(Cu2)=45.5±2.2 kcalD00(AgAu)=47.6±2.2 kcalD00(Ag2)=37.6±2.2 kcalD00(AgCu)=40.7±2.2 kcalD00(Au2)=51.5±2.2 kcalD00(AuCu)=54.5±2.2 kcalThese are based on ΔH298vap=81.1, 68.4, and 87.5 kcal/g-atom for Cu, Ag, and Au where D00 of AgCu depends on the value for Cu, and D00 of AgAu and AuCu on Au. The uncertainties quoted do not include the uncertainty in ΔHvap.
Solar occultation observations of the Martian atmosphere near the limb of the planet were performed during the P/whos mission by means of the Auguste infrared spectrometer in the ranges 2707-3740 and 5391-5272 cm ' with a resolving power of 5 1300. The spectra exhibit features at 2710 and 1730 crn~-' which have not been identified previously. After applying a set of corrections to the data and examining the spectra of various molecules, we are led to conclude that the best candidate for the above-mentioned features is formaldehyde (CH?O). It was observed in eight of the nine successful occultation sequences. mainly between 8 and 30 km with an average mixing ratio of 0.5ili : ppm (there are no good data below 8 km). The observations are performed in equatorial spring conditions. The altitude distribution of formaldehvde reveals correlation with the permanent haze opacity.
HCl has been observed in the stratosphere from balloon borne spectroscopic measurements of a portion of the fundamental band in the 3 microns wavelength region. The observation of absorption lines using the sun as a source at solar zenith angles larger than 90° indicates an HCl volume mixing ratio equal to (3.8 ± 1.5) × 10−10 at 20 km increasing with altitude at least up to 30 km where the value is (1.4 ± 0.6) × 10−9. The total zenith amount above 21 km is found to be (10± 3.5) × 10−14 cm−2 in agreement with previous observations performed up to this altitude. A maximum number density equal to (7.2 ± 3) × 108 cm−3 is observed at 24 ± 2 km altitude.
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