R.R. Jones, S.N. Pisharody, and R. van Leeuwen
Abstract:Atoms with two optically accessible electrons provide pristine systems for testing the limitations of laser control scenarios. We present the results of two experiments in calcium in which ultra-short laser pulses are used to pump population from the atomic ground state into a non-stationary, singly excited wavepacket. After the system has evolved, a second short pulse dumps the bound population into a number of degenerate continua by resonantly driving the system into a rapidly decaying autoionizing configuration. In one experiment, autoionization from a radially localized Rydberg wavepacket is found to be non-exponential in time, occurring in a series of discrete steps. This phenomenon is explained using a simple intuitive picture of the time-dependent interaction of the Rydberg wavepacket with the other electron. In a second experiment, control of the angular distribution of electrons ejected during the autoionization of angularly localized wavepackets is examined. Only limited control is observed due to significant coupling between continuum channels as the system fragments.
Published in "Laser Control and Manipulation of Molecules", ACS Books, R.J. Gordon, A. Bandrauk, and Y. Fujimura, eds.(2001).