Ultrafast Picometer-Resolved Molecular Structure Imaging by Laser-Induced High-Order Harmonics.

Area of Science:

• Ultrafast optical science
• Physical chemistry
• Molecular imaging

Background:

• Real-time molecular transformation visualization is crucial but challenging.
• Current methods like X-ray and electron diffraction lack sufficient temporal resolution (hundreds of femtoseconds).
• Few-femtosecond temporal resolution is needed to probe ultrafast molecular dynamics.

Purpose of the Study:

• To develop a method for imaging molecular transformations with attosecond temporal resolution.
• To achieve few-picometer spatial resolution for detailed molecular structure analysis.
• To demonstrate the capability of high-harmonic structure imaging (HHSI) for ultrafast molecular dynamics.

Main Methods:

• Generating high-order harmonics from intense femtosecond lasers.
• Exploiting the dependence of molecular recombination dipole moment on molecular geometry.
• Applying HHSI to monitor structural rearrangements in NH3, ND3, and N2.

Main Results:

• Achieved few-ten-attosecond temporal resolution and few-picometer spatial resolution.
• Successfully monitored structural rearrangement in NH3, ND3, and N2 within femtoseconds.
• Demonstrated the effectiveness of HHSI for ultrafast molecular dynamics.

Conclusions:

• HHSI provides unprecedented spatiotemporal resolution for molecular dynamics.
• This technique can resolve molecular structural changes in real-time.
• HHSI holds potential for future studies of photochemical reactions.