The role of molecular and resonance phases in the coherent control of chemical reactions

Abstract

Coherent control of the photoionization and photodissociation of HI and the photoionization of H₂S were obtained in the region of the 5d(π, δ) resonance of HI. Interference between one- and three-photon excitation paths caused modulation of the HI⁺, I⁺, and H₂S⁺ signals. Phase lags between the different modulated signals, measured as a function of excitation energy, revealed the roles played by molecular and resonance phases. A theory of the phase lag arising from a set of overlapping rotational resonances was developed and used to interpret the observations.