An examination of negative fragment ions formed by resonance capture processes has been made using a mass spectrometer. It has been found in some cases that the various fragments for a particular molecule arise at the same ionizing energy, possibly by competing decomposition paths from the same state of the n;gative molecular ion. Other cases where the fragments do not arise at exactly the same energy may be explamed by close upper energy states of the negative molecular ion.. In general the observed ionization energies are greater than those calculated from the energies of bo~ds broken and electron affinities. Kinetic energy measurements on some of the more abundant fragments, I.e., CI-(CC4, CHa• CH2CI· CO) , 0-(S02, CO2, N20, NO), show that this excess energy is not translational.

Double and triple ionization by electron impact in molecules is examined and, as was found for the monatomic gases, the data support the view that the threshold law for the probability of double ionization is a square-law function of the excess electron energy. Some excited states have been detected, and autoionization does not seem to be important. The vertical potentials for all the processes of multiple ionization observed have been measured. The relative electronic-transition probabilities for single, double, and triple ionization are compared. The factors affecting the stability of multiply charged molecular ions are discussed, and an attempt is made to correlate the electron impact data with the molecular structures. It is shown that Coulomb repulsion between the separated charges causes the potential energy functions describing these ions to be of unusual form.

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Fossil marine shells collected in southern Victoria within half a degree of latitude of 38(1/2) degrees S have been analyzed for O(18)/O(16) by mass spectroscopy, and their paleotemperatures have been determined. For the genera Chlamys, Ostrea, and Glycymeris the temperature rises from early to mid-Tertiary, then falls again to the present.

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