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The fragmentation of CF4+ ( X 2T1), CF4+( A 2T2), N2O+( A 2Σ+) and COS+ ( A 2Π) all involve the release of large kinetic energies. Details of these and other fragmentations studied by the coincidence method are reported and discussed in relation to other experimental findings. The kinetic energy release in formation of CF3+ from CF4+ ( X 2T1) sets a new upper limit of 14.84±0.05 eV on the dissociation asymptote. A new metastable in the electron impact mass spectrum of COS, predicted from a previous coincidence result, is also reported.

The 21.22-eV photoelectron spectrum has been measured from a barium beam. Aside from the ground state of Ba + , the first six excited states of this ion have been identified. An unusually high relative cross section for the production of Ba 2+ and excited Ba + compared to Ba + in its ground state is found. An explanation is proposed involving the autoionizing (5p) 5 (6s) 2 2 P 1/2 state of Ba + . From this the binding energy of the 5P 1/2 electrons of Ba is found to be 21.1 eV.

Carbon disulphide ions initially produced by photoionization in the C (2Σg+) and D (2Σu+) states are shown to decompose to all the energetically possible products, and branching ratios for the different processes are given. The kinetic energy release distributions for the five fragmentations have also been measured. The results are discussed in terms of rapid internal conversion processes preceding predissociation.

Photoelectron spectra measured with 21.22 eV and 12.08 eV light are used to determine the contribution of autoionization processes to the photoionization cross sections of methanol and ethanol. The most important of fragmentation processes of the molecular ions are investigated using the technique of measuring photoelectron spectra in coincidence with mass-analysed ions. It is shown that some structures observed in the photoionization cross sections of these molecules are due to autoionization processes rather than to isolated electronic states of the ions.

Five electronic states of the diborane ion are observed in the photoelectron spectrum of diborane using the 584 A He resonance line and a planar retarding-field, spectrometer.