The vibronic bands in the dipole-allowed absorption spectrum of N2 associated with the lowest three electronic 1Σ+u and the lowest three electronic 1Πu states are represented in a basis of electronically coupled diabatic states as well as in the basis of nuclear-momentum coupled adiabatic states. Parameters defining the diabatic states and their electronic coupling energies are first evaluated by fitting the eigenvalues of a vibronic interaction matrix to the observations. The coupled-oscillator equations are then solved directly by Johnson’s numerical integration method and the diabatic representation is redetermined via the matrix method and coupled equations iteratively. The fit of the experimental vibronic terms, B values, and absorption intensities achieved with R-independent electronic coupling energies in a diabatic basis of valence and Rydberg-type states (b′+c′+e′)1Σ+u and (b+c+o)1Πu is satisfactory. Comparison with the corresponding adiabatic representation shows that the nonadiabatic perturbations are larger in that basis than in the diabatic one. The vibronic intensity distributions observed in the absorption spectrum show numerous interesting examples of intensity envelopes over discrete vibronic progressions with Fano-type resonance profiles as well as with distinctly non-Fano-type profiles which can be attributed to variations of the relevant coupling terms over the widths of the vibronic resonances.
A 'Be identifier of high detection efficiency was utilized to investigate the (n, 'Be) reaction on ' 0, "N, "N, "C, ' C, "B, ' 8, and Be targets at bombarding energies between 65 and 72.S MeV. Differential cross sections were measured from 8, = 20'-70' for solid targets and over a more restricted range for the nitrogen gas targets. Excitation functions were obtained over a larger energy range for the "C and ' 0 targets. At these energies, the (a, 'Be) reaction was found to proceed predominantly via a direct a-cluster pickup mechanism and to populate strongly only those levels consistent with this. mechanism. The data mere analyzed in the framework of the exact finite-range distorted-wave Born approximation. Absolute and relative a-particle spectroscopic factors were extracted for 22 states. Good agreement was found between these experimental values and the theoretical predictions of Kurath and of Rotter for the extent of e clustering in these light nuclei.
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