PhD Dissertation Defense

We present studies of the generation, observation and manipulation of vibrational coherence with ultrafast lasers and investigations of molecular structure and dynamics using vibrational wave packets.

We show the experimental results of vibrations in ion signals and the kinetic energy of the fragment ions. The host state for the vibrational wave packet and the creation mechanisms are determined through frequency analysis and the phases of the vibrations. Also, we simulate the motion of the wave packets, which agree with the experimental results and are used to map the measured kinetic energy to the internuclear separation and give predictions of the vibrations' dependence on laser pulse parameters.

Comparing the results of the vibrations for hot molecules with cold molecules, it is found that initial thermal excitation of vibrational levels is not detrimental to vibrational coherence for Lochfrass or the "R-dependent ionization" creation scheme. In fact, Lochfrass can lead to vibrational cooling, as well. Whereas for bond softening, a coherent interaction, the initial thermal population is detrimental to producing coherence. Using the vibrational motion, potential curves of ionic molecular states are investigated and we are able to trap molecules in the potential well of an excited molecular state of doubly ionized molecular iodine. Moreover, the internuclear separation dependent ionization of an excited state of neutral iodine is studied with large amplitude vibrational motion. Finally, multiphoton excitation of molecular ions is observed with dissociative vibrational wave packets.