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The Rydberg spectrum of Na2 has been shown previously to alternate when increasing energy between ‘‘stroboscopic fringes’’ which correspond to a well known separable Hund’s coupling case (a), and a complex, unidentifiable intermediate coupling. We use this system as a prototypic example to test some current ideas on the correspondence between classical chaos and properties of quantum spectra. We first determine the phase space structure and transition to chaos in classical mechanics. We then determine the change in line intensities and level spacing statistics in quantum mechanics. We show that this system has the expected behavior in the semiclassical limit in the presence of classical chaos, except for a peculiarity in level spacing statistics, but that this behavior is not a signature of chaos, since the same system shows similar behavior for some values of the parameters which correspond to a nonchaotic situation in classical mechanics. We discuss also some problems related to the nonvalidity of the semiclassical limit. [ABSTRACT FROM AUTHOR]

Similar populations have been observed between the A and X states of the CN radical, formed in the C+N2O chemical reaction. Relative vibrational populations were measured by laser-induced fluorescence (X state) and chemiluminescence (A state). The electronic branching ratio was then obtained by assuming a Boltzmann equilibrium between the v‘=4–6 and v’=1–4 levels of the X and A states. This assumption was checked by absolute calibration of the number densities of both states. About 1/3 of the radicals were found in the A state. [ABSTRACT FROM AUTHOR]