Professor Warren is supported by a grant from the Experimental Physical Chemistry Program to use shaped laser pulses to orient or align molecules in a molecular beam, to generate population inversion in low-temperature crystals, and to localize energy in a bond by a photon-locking experiment. One of the thrusts of the research program is the development of techniques to efficiently populate an electronically excited state with a single laser, or to transfer population to highly vibrationally excited levels of the ground state with two lasers. The motivation for this work is the study of collisional dynamics which require selective excitation to monitor velocity changing collisions. Complete population transfer enhances the signal and minimizes interferences. Success in transferring large fractions of the thermal distribution into high vibrational states will be useful for exploring the kinetics of chemical reactions. One goal is to design radiation fields which drive diatomic molecules in their ground state to a superposition of rotational states such that the diatomic molecule is oriented in the laboratory. A demonstration of the effect of modulating the dissociation rate of the IBr molecule by Stark shifting previously stable levels with specific frequency-swept pulse shapes will be the first step towards applying this technique to polyatomic molecules. %%% By preparing specially tailored pulses of light, it is possible to produce simple and interpretable states of molecules. These techniques will be used by Prof. Warren to control their alignment in a molecular beam and even their orientation in the laboratory, and to modulate the rate at which they break apart into fragments.
