Nonlinear mechanics of molecular vibrations and mechanism of collisionless dissociation in a high-intensity laser field

The problem of a resonant interaction of a molecular vibration mode with a high-intensity laser field is considered, and quasi-energies as well as corresponding wave functions are found. A close relationship is established between the classical theory of spontaneous phase locking with the theory of resonant Stark broadening. Coherent interaction between modes of polyatomic molecules via random high-order Fermi resonances, resulting in energy exchange between these modes, is discussed. This interaction is found to be very similar to the phenomena observed in nonlinear chains studied in numerical experiments. The condition for loss of coherence and transition to unbounded diffusion-type energy acquisition, similar to the Chirikov stochastic criterion in mechanics, is discussed.