HARMONIC AND NONHARMONIC FREQUENCY GENERATION BY MOLECULAR VIBRATIONS STRONGLY DRIVEN BY LASER-RADIATION

The power spectrum of radiation emitted by a Morse oscillator strongly driven by an intense laser pulse is calculated numerically. It is shown that at laser intensities close to the dissociation threshold, instead of the usual harmonic generation one observes a strong generation of a discrete but dense spectrum. This is a manifestation of resonant nonperturbative effects and can be viewed as a signature of chaotic behavior of the system. The present results suggest the use of nonharmonic generation to measure the onset of chaos in radiation-matter interactions.