Imaging an isolated water molecule using a single electron wave packet.

Area of Science:

• Physical Chemistry
• Molecular Dynamics
• Ultrafast Spectroscopy

Background:

• Observing molecular structure dynamics requires high spatio-temporal resolution.
• Atomic-scale and femtosecond resolution are crucial for tracking molecular changes.

Purpose of the Study:

• To directly retrieve the molecular structure of H2O+ with high resolution.
• To study the nuclear response of water molecules to external laser fields.
• To understand the coupling between molecular geometry and intense laser fields.

Main Methods:

• Utilized the Fourier transform (FT) variant of laser-induced electron diffraction (LIED), termed FT-LIED.
• Achieved picometer and femtosecond resolution without prior structural knowledge or complex algorithms.
• Applied external laser fields of varying strengths (2.5 to 3.8 V/Å) to isolated water molecules.

Main Results:

• Directly retrieved the molecular structure of H2O+ with unprecedented resolution.
• Identified a symmetrically stretched, field-dressed H2O+ structure likely in the ground electronic state.
• Observed O-H bond stretching and molecular bending in response to increasing laser field strength.

Conclusions:

• Ultrafast structural changes increase the dipole moment of water molecules.
• A stronger dipole interaction occurs between the nuclear framework and the laser field.
• Provides insights into laser-matter interactions and molecular response to external fields.