Sum frequency and second harmonic generation from the surface of a liquid microjet

Area of Science:

• Nonlinear optics
• Surface science
• Spectroscopy

Background:

• Investigating liquid surfaces requires advanced spectroscopic techniques.
• Nonlinear optical methods like SHG and SFG provide surface-specific molecular information.

Purpose of the Study:

• To explore the utility of liquid microjets as a source for nonlinear optical spectroscopy (SHG and SFG).
• To analyze the SHG scattering patterns from a water microjet and the SFG spectra from an ethanol microjet.

Main Methods:

• Measured non-resonant Second Harmonic Generation (SHG) scattering patterns from a pure water microjet.
• Performed Sum Frequency Generation (SFG) experiments on an ethanol microjet surface.

Main Results:

• Observed significant enhancement of the SHG signal from the water microjet at specific angles, attributed to optical properties and jet shape.
• Successfully measured coherent vibrational SFG spectra from the ethanol/air interface using the microjet.

Conclusions:

• Liquid microjets are a viable and effective source for SHG and SFG spectroscopy of liquid surfaces.
• This method is promising for future far-UV/X-ray nonlinear optical surface experiments and combined spectroscopy techniques.