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Chaotic autoionization of molecular Rydberg states

In ref. [64] an energy exchange between a Rydberg electron and a molecular core is investigated in the regime where the Born-Oppenheimer approximation is violated. The theory developed allows the possibility for a strong energy exchange even for high orbital momentum of the electron when quantum defects are small. This regime is completely different from the regime studied by Labasti, Lombardi and Seligman when electon is colliding with the core and only small orbital momenta are mixed. Basing on Kramers-Henneberger transformation it is possible to connect Rydberg molecule problem with the problem of microwave ionization. Here the frequency of molecular rotation $\omega$ plays the role of microwave frequency while the effective electric field is given by the dipole moment of the molecule ( $\epsilon = d \omega^2$). This connection of two problems allows to find a classical border of chaotic ionization and a quantum delocalization border above which strong autoionization takes place. Similar effects, as discussed in [77], can take place in atomcule (helium atom in which one electron is replaced by antiproton) where antiproton has high quantum numbers and moves quasiclassically. It is interesting to note that this system gives a physical example of conservative model in which eigenstates can be localized on energy surface while a classical trajectory diffusively cover the whole energy surface. This should lead to Poisson statistics of levels instead of Wigner-Dyson distribution. A similar situation happens in rough billiards studied in [89,92] (see discussion in the next Section). It is interesting to note that the classical energy exchange between rotating core and electron is very similar to the energy variation of Halley's comet produced by Jupiter. Indeed, as had been shown by Chirikov and Vecheslavov the dynamics of Halley's comet is described by a map very similar to the Kepler map. In this sense the autoionization of molecular Rydberg states simulates ionization of a quantum comet.


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Next: Recent Results Up: Other Directions of Researches Previous: Nonlinear wave propagation in   Contents

2000-01-04