Electronic coherences in molecules measured with phase-locked pulse pairs in the deep ultraviolet*

Electronic coherences are at the heart of attosecond science and our understanding of coupled electron-nuclear dynamics in molecules. However, electronic coherences tend to decay rapidly in molecules due to nuclear motion and the coupling between electronic and nuclear degrees of freedom. Recent work has demonstrated the possibility of observing long-lived coherences in molecules with parallel potential energy surfaces. Here we present a new apparatus for creating and measuring electronic coherences in molecules by using shaped, few-cycle laser pulses in the deep ultraviolet. Previous work utilized multiphoton resonance to couple parallel excited states; now we are able to use the ultraviolet light to couple states with single-photon resonance. We present measurements on a series of molecules, which are interpreted with a simple model that makes use of the simplicity of the single-photon coupling.