The dynamics of high Rydberg states in the presence of time-dependent inhomogeneous fields

This paper presents calculations of the evolution of an optically prepared Rydberg wavepacket in the presence of time-dependent inhomogeneous electric fields and the results have relevance to the stabilization of Rydberg states as appropriate to ZEKE spectroscopy. The field is considered to arise from the combination of an applied field, which may be ramped in time, and the presence of microscopic charges, e.g., a pseudo-random distribution of ions, whose positions may also change with time. The results of the calculations lead to a clearer definition of the conditions under which Rydberg stabilization is achieved, such as in field switching experiments (Baranov et al., Chem. Phys. Lett., 1998, 291, 311), and also confirm the mechanisms by which the randomization of population between blue-shifted and red-shifted Stark states occurs in the presence of micro-fields due to ions (Palm et al., Philos. Trans. R. Soc. London, Ser. A, 1997, 355, 1551). The motion of the ions is found to have a significant m-locking effect in the calculations, providing a possible mechanism for the commonly observed long-lifetime tail in the population decay of high-n Rydberg states.