A microfluidic liquid sheet apparatus for extreme ultraviolet high-order harmonic generation

Area of Science:

• Ultrafast science
• Nonlinear optics
• Photonics

Background:

• High-order harmonic generation (HHG) is a key ultrafast light source.
• Extending HHG from gases to liquids presents significant technical challenges.
• Recent attention is focused on developing HHG techniques for liquid samples.

Purpose of the Study:

• To report an apparatus for extreme ultraviolet (XUV) HHG from microfluidic liquid sheets.
• To investigate the feasibility and parameters of HHG in liquids.
• To explore potential applications in studying liquid-phase chemical reactions.

Main Methods:

• Generation of a microfluidic liquid sheet using a borosilicate glass chip (9 mm x 2 mm x 1 μm).
• Excitation of the liquid sheet with intense femtosecond laser pulses.
• Systematic study of HHG dependence on laser parameters (wavelength, intensity) and focusing position.

Main Results:

• Successful production of HHGs up to 20 eV from water, methanol, and ethanol liquid sheets.
• Detailed analysis of the influence of laser parameters and focusing on HHG.
• Demonstration of HHG as a potential tool for probing electron radiation-induced chemical reactions in liquids.

Conclusions:

• The developed apparatus enables XUV HHG from microfluidic liquid sheets.
• HHG in liquids is controllable by laser parameters and focusing.
• HHG spectroscopy offers a promising avenue for investigating ultrafast chemical dynamics in liquids.