The ability of a harmonic barrier to support resonances is examined. Stabilization graphs calculated from box quantization have the features expected for resonances at an energy equal to the barrier maximum. The search for a wave packet of maximum lifetime leads also to this energy. These findings agree with the energies associated with the poles of the S matrix.

INFRARED-MICROWAVE DOUBI E RESONANCE ACKNO'WLEDGMENTS %e %'lshto thank F. Shimizu fol informing us of the results of his laser spectroscopic studies of 4NH3 and 15NH3 prior to publication. We are also indebted to K. Shimoda and C. C. Costain forhelpful discussions and to

Accurate numerical methods are applied to the vibronic problem resulting from bvo interacting intGI"86cting hRrInonlc cuI'ves. 7%"o GXRInples Rle considered, corresponding to either degenerate or nondegenerate electronic states. The energies are obtained ruth (a) the zerothorder Born-Oppenheimer appxoximation; (b) the so-called adiabatic approximation, which includes the di, agonal corrections to (a); (c) the full vibronic procedure. Several featuxes in the correlation diagrams giving tIM eneI'gie8 Rs R function of the configuration-intGI'action Matrix element aI'e given an explanation.We also note that, in the model treated here, inclusion of the diRgonRl corI'Gctlons does not always lead to Rn lmproveInent of the eneI'gies,

No abstract

On the molecular theory of aqueous electrolyte solutions. III. A comparison between Born-Oppenheimer and McMillan-Mayer levels of descriptionAfter showing in a previous paper that the Born-oppenheimer zeroth-order approximation can produce accurately the vibronic energies of a model of an excited molecular dimer for a wide range of parameters, the same approach is now used to calculate the vibrational patterns in absorption and fluorescence spectra. Two different levels of approximation depending on the degree of adiabaticity of the electronic wavefunctions are compared with the vibronic treatment. The progressions in the spectra are interpreted in terms of Franck-Condon factors, vibrational borrowing, and vibronic coupling between Born-oppenheimer product wavefunctions.