Controlling the interference of multiple molecular orbitals in high-harmonic generation

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Optics
• Laser Physics

Background:

• High-harmonic generation (HHG) is a key process for producing extreme ultraviolet and X-ray light.
• Understanding the factors influencing HHG spectra is crucial for controlling light generation.
• Spectral structures in HHG provide insights into electron dynamics and molecular properties.

Purpose of the Study:

• To demonstrate a novel method for investigating the origins of spectral structures in high-harmonic generation.
• To analyze the influence of molecular orbitals and structural characteristics on HHG spectra.
• To provide a versatile approach for studying HHG in complex molecular systems.

Main Methods:

• Detailed measurements of high-harmonic spectra were performed on aligned nitrogen (N2) and carbon dioxide (CO2) molecules.
• The wavelength and intensity of the generating laser field were systematically varied.
• Quantitative analysis was employed to correlate spectral features with molecular properties.

Main Results:

• The spectral minimum in aligned N2 molecules remained largely unaffected by changes in laser parameters.
• The spectral minimum in aligned CO2 molecules exhibited a significant shift exceeding 15 eV.
• Analysis indicated that both multi-orbital interference and molecular structural characteristics determine the position of the spectral minimum.

Conclusions:

• The developed method offers a straightforward approach to probe HHG in more complex molecules.
• Orbital interference and molecular structure are critical factors shaping HHG spectra.
• This work advances the understanding of electron dynamics in laser-driven molecules.