Quasiresonance

Abstract

The concept of quasiresonance was introduced in connection with inelastic collisions between one atom and a vibro-rotationally excited diatomic molecule. In its original form, the collisions induce quasiresonant transfer of energy between the internal degrees of freedom of the diatom: there is a surprisingly accurate low order rational value for the ratio of the changes in the vibrational and rotational classical actions, provided the vibrational and rotational frequencies of the diatom are approximately related by low order rational values, and the collision was longer than the rotational period of the molecule. In this paper, we show that quasiresonance can be extended to many other processes and systems, and that it may be understood in terms of the adiabatic invariance theory and the method of averaging.

Acknowledgements

This paper is submitted in honour of and in the spirit of the many deep contributions of Professor Mark Child to classical physics associated with molecular and quantum systems.

AR would like to thank Robert Parrot, Diego V. Bevilaqua and Daniel Alonso for many fruitful discussions. AR gratefully acknowledges the hospitality of the Physics Department of Harvard University, where the present work was carried out. AR was supported by a MECD/Fulbright grant from Secretarìa de Estado de Educación y Universidades and, partially, from Fondo Social Europeo. This work was also supported by a grant from the National Science Foundation, NSF CHE-0073544.