A theoretical study of the bond-bond interaction force constant in XF2 molecules
A comparison of the results of a semi-empirical molecular orbital calculation for OF2 with the empirical interaction force constants for OF2, NF2 and CF2 leads to the conclusion that electron delocalization, of a type commonly identified as no bond-double bond resonance, strongly influences the magnitude of the interaction constants for these molecules. This analysis further suggests that Urey-Bradley fluorine-fluorine non-bonded interaction constants for polyfluorinated molecules may commonly be inflated by such resonance. It was expected that the MO calculation would also help clarify the origin of the unusual stability of polyfluorinated systems, but the results are largely inconclusive on this point.
Abstract : The results of experimental investigations to evaluate the fatigue properties of Mo + 0.5 wt-% Ti are presented. Tests were conducted with specimens in potassium vapor and in vacuum at 1500 and 2000 F to determine what effect, if any, the potassium vapor would have on the fatigue properties of this alloy. The results of these tests indicate that the fatigue strength of Mo + 0.5 wt-% Ti is reduced when this alloy is subjected to the conditions of these tests. (Author)