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Photoelectron spectra of valence shell electrons in F2, Cl2, Br2, and I2 yield information on the molecular and electronic structure of the lowest several states of the corresponding positive ions, some of which is not available from previous spectroscopic studies. Spin–orbit fine structure is resolved for the ground Π21 states of F2+ and Cl2+; values obtained are ζ = 337 ± 40 and 645 ± 40 cm−1, respectively. The first excited states of the ions are identified as Π2u and approximate values of ζ = 2000–2200 and 6400 cm−1 obtained for Br2+ (A 2Πu) and I2+(A 2Πu), respectively. A state in F2+ reported previously [D. C. Frost, C. A. McDowell, and D. A. Vroom, J. Chem. Phys. 46, 4255 (1967)] to lie at ∼ 17.4 eV is not observed here and is attributed to nitrogen impurity. Vibrational frequencies for F2+ and Cl2+(X 2Πg) are in agreement with spectroscopic work. The corresponding frequencies for Br2+ and I2+ are ωe = 360 ± 40 and ∼ 220 cm−1. A change in bond length to Br2+(2Πg) of Δre ∼ (−)0.095 Å is estimated from the vibrational envelope of the X2Πg state of Br2+.

Photoelectron spectra of methyl chloride, methyl bromide, and methyl iodide obtained with 584-Å radiation yield in each case four of the five valence-shell ionization potentials. Values of 11.29, 10.53, and 9.50 eV are obtained for the first ionization potentials, respectively, corresponding to ionization from halogen “lone-pair” orbitals. Resolved vibrational structure allows determination of frequencies of the corresponding normal vibrations of the positive ions in several cases. Relative intensities of vibrational components in the first ionization potential are dictated by vibronic interaction. Approximate values of the Jahn–Teller parameters D for ν4, ν5, ν6 in CH3Br+ may be obtained from these intensities. Small values of D (D ≤ 0.1) suffice to produce sizeable modifications of intensity for the intermediate spin–orbit splittings observed in these ions.

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Deuteron NQR spectra of several model systems involving alcoholic of phenolic-OD groups are discussed. The spectra of alpha hydroquinone and its two isomers resorcinol and catechol show complex structure due to the presence of inequivalent O–D⋅⋅⋅O hydrogen bonds. In the case of hydroquinone, this structure collapses to that characteristic of a single type of hydrogen bond in the beta- or clathrate-forming phase. An attempt is made to place the data in theoretical perspective by calculations of the deuterium field gradient in hydroxide ion, hydroxyl radical, methanol, and methanol dimer and by comparison with precise Hartree–Fock computations from the literature.