IONIZATION MECHANISMS OF ONE-DIMENSIONAL OSCILLATORS IN HIGH-FREQUENCY FIELDS

The effect of a high-frequency field on the motion of a one-dimensional anharmonic oscillator is studied. Various types of ionization mechanism are considered in both classical and quantum dynamics and it is shown that for sufficiently high-frequency fields the classical system can ionize through regular orbits. The authors construct a general area-preserving map which approximates the dynamics and obtain an explicit quantization of this approximation in terms of the Fourier components of the classical motion. This provides a very efficient approximation to the solution of the time-dependent Schrodinger equation. The authors consider the Morse oscillator in detail, showing that the classical map agrees well with the numerical solution of Hamilton’s equations. Classical and quantal ionization probabilities are compared and the authors delineate circumstances where they do and do not agree. © 1990 IOP Publishing Ltd.