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New sharp bands of formic acid have been observed in the near ultraviolet at the long wave-length end of the previously observed diffuse band system (2250–2500 A) by considerably extending the absorption path length. Both the diffuse and sharp bands belong to the same vibrational system which is assigned to the π ∗ ← n electronic transition in the carbonyl group. Extensive progressions are observed in the carbonyl stretching frequency which is greatly reduced in the excited state (fundamental ν3′ ≈ 1080 cm−1) and many intervals of about 400 cm−1 are assigned to the OCO bending frequency ν7′. A band contour analysis of the 2593 A band shows that the molecule is nonplanar in the excited state because of the magnitude and sign of the inertial defect. From this analysis, the rotational constants for the excited state are S ‘ =1.8755, B ‘ 0.4042, C ‘ =0.3378 cm −1 By the plausible assumption that the important changes in the molecule are in the C=0 bond length, the OCO angle, and the nonplanarity due to the formyl hydrogen, the following excited state parameters are derived.rC=0 = 1.407A.The changes in formic acid are closely analogous to the changes in formyl fluoride as a result of the π ∗ ← n transition.

Accurate eigenvalues and selected eigenvectors are presented for the three-dimensional isotropic quartic oscillator in the representation of the three-dimensional isotropic harmonic oscillator. They were determined by means of the linear variation method, and matrices of large order were diagonalized by using efficient procedures. This work rectifies an error in the calculations of Lu and Nigam (1969), which results in only half of their energy levels being the true solutions of the quartic oscillator problem.

Accurate eigenvalues and eigenvectors of the one- and two- dimensional quartic oscillators have been determined using the linear variation method in which the Hamiltonian matrix was set up in the representation of the corresponding harmonic oscillator. The Hamiltonian matrix was factorized and the submatrices were diagonalized using two different methods: (i) Matrices of order 100 were diagonalized giving both eigenvalues and eigenvectors. (ii) Matrices of order 800 were diagonalized giving eigenvalues only. The former of these procedures yields eigenvalues accurate to nine figures. Mixed harmonic-quartic potentials have been investigated for the two-dimensional case.

A new emission system of CS has been observed in the vacuum and near ultraviolet produced by a microwave discharge in carbon disulphide. The system arises from the transition A ′ 1 Σ + -X 1 Σ + . Twelve vibrational levels of the X state and nine levels of the A ′ state have been observed and rotational constants obtained for most of them. The following vibrational and rotational constants have been derived for the A ′ state: ω e =462.4, ω e χ e =7.46, ω e Y e =−0.108, ω e Z e =0.0377cm − 1, β e =0.5114, α e =0.0109, γ e =0.00112, δ e =0.000208cm − 1. From these constants we derive r e ′ = 1.944 ± 0.001A, T 0 = 56093cm −1 and D 0 ′ = 3270cm −1 , and hence an accurate value is found for the ground state dissociation energy, D 0 ″ = 59320 ± 100cm −1 .

The assignment of the first vacuum ultraviolet transitions in formaldehyde is re-examined. The transition at 1750 A is established as 1B2(n, 3s) ← X 1A1, and, by correlation with the photoelectron spectrum, a progression in νi = 2660 ± 20 cm−1 can be identified. The bands at 1556A and 1525A are assigned to 1A1(n, 3py) ← X 1A1, and 1B2(n, 3pz) ← X 1A1 respectively. Assignment of the excited state frequencies ν′3 = 757 ± 20 cm−1 and ν′6 = 206 ± 20 cm−1 is made for the first system of the D2CO spectrum.

Discrete vibrational structure has been observed in the vacuum ultraviolet spectra of cyclopentane and cyclohexane.

Octafluoroisobutene reacts with pentafluoropyridine in the presence of fluoride ion, at 80°, to give perfluoro-2,4,6-tri-t-butylpyridine whereas, at 20°, perfluoro-4-t-butylpyridine is formed. Reaction of Octafluoroisobutene with tetrafluoropyridazine, at 80°, gives perfluoro-3,6-di-t-butylpyridazine exclusively, although at lower temperatures perfluoro-4-t-butyl or-3,5-t-butyl derivatives are obtained. The variation in the orientation of products formed with the olefin used in polyfluoroalkylations with tetrafluoropyridazine is discussed. Perfluoro-t-butylpyridines show no indication of restricted rotation even at low temperatures and this illustrates how increased crowding can lower a rotational barrier.