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Gamma-irradiated polycrystalline CCl4 at 77°K provides evidence that positive charge migrates and is trapped by the matrix itself. The trapped positive hole absorbs at about λmax=400 mμ in pure CCl4 or dilute solid solutions of aromatic amines. The solvent band is depressed by aromatic amines or other additives which act as hole traps with appearance of the corresponding amine cation absorption. After γ irradiation the residual 400-mμ band photobleaches at 77°K with increase in solute cation absorption. Brief heating to 143°K gives the same result. A kinetic treatment which assumes that the only labile species in the system is migrating positive charge can explain the experimental results in a satisfactory way. The kinetic analysis gives a rough estimate of total available positive charge created per 100 eV of absorbed energy as 1.9. Several aromatic amines have been used as test substances and their optical absorption spectra recorded.

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Photoionization cross sections in resonance ionization mass spectrometry of sputtered metal atoms: Applications to material analysis Proton transfer is the most probable type of reaction observed in a number of ion-molecule interactions involving permanent dipoles. Integrated cross sections, which are unusually large, are described in terms of an ion-dipole pair oriented near the position of minimum energy at low relative velocity. As the relative velocity is increased, this alignment becomes less likely. The energy-dependent cross section is eclipsed at high relative velocity by the "hard" cross section which does not vary with energy. Proton affinities are estimated for several alkyl cyanides. Some of the reported reactions appear to involve excited states of the primary ions.