A pump–probe scheme with a single chirped pulse to image electron and nuclear dynamics in molecules

Abstract

A single chirped few-femtosecond pulse can be used to control and image coupled electron-nuclear dynamics. Using full ab initio simulations of the simplest molecule, ${{\rm{H}}}_{2}^{+},$ as a prototype target, we show that for intermediate values of the chirp, interference between sequential and direct contributions enables significant control over ionization yields, even when taking into account the effective decoherence introduced by nuclear motion and the presence of an electronic continuum. For larger values of the chirp, the single chirped pulse reproduces a classical pump–probe setup, with the chirp parameter mapping an effective time delay between the pumping and probing frequencies of the pulse. After demonstrating this numerically, we present a full analytical solution for the two-photon ionization amplitudes that provides an intuitive analogy between the molecular dynamics induced by a single chirped pulse and a traditional pump–probe setup.

Keywords

• multiphoton molecular ionization
• frequency-chirped pulses
• attosecond science
• electron-nuclear coupled dynamics