Imaging the Temporal Evolution of Molecular Orbitals during Ultrafast Dissociation

Area of Science:

• * Molecular dynamics
• * Ultrafast spectroscopy
• * Atomic and molecular physics

Background:

• * Understanding molecular dissociation dynamics is crucial for controlling chemical reactions.
• * Auger electron spectroscopy provides insights into electronic structure changes during molecular events.
• * Ultrafast laser techniques enable the study of transient states in chemical processes.

Purpose of the Study:

• * To investigate the temporal evolution of Auger electron angular distributions in HCl.
• * To characterize the transformation of electron emission patterns during ultrafast dissociation.
• * To correlate electronic state changes with molecular fragmentation dynamics.

Main Methods:

• * Resonant single-photon excitation of HCl molecules.
• * Time-resolved Auger electron spectroscopy.
• * Molecular frame angular distribution analysis.

Main Results:

• * Observed a dynamic change in electron emission patterns during HCl dissociation.
• * The angular distribution evolved from a molecular sigma (σ) orbital signature to an atomic p-state signature.
• * This evolution reflects the transition from a bound molecule to separated atomic fragments.

Conclusions:

• * The study successfully tracked the electronic state evolution during ultrafast molecular dissociation.
• * The observed changes in Auger electron angular distributions provide a clear signature of the dissociation process.
• * This work offers a detailed view of the molecular-to-atomic transition in real-time.