Characterization of a vacuum ultraviolet light source at 118 nm

Area of Science:

• Atomic and Molecular Physics
• Laser Spectroscopy
• Chemical Physics

Background:

• Vacuum ultraviolet (VUV) light at 118 nm is a valuable tool for ionizing molecules in gas-phase chemical studies.
• Table-top sources of 118 nm VUV light can be generated via frequency tripling of 355 nm light from a Nd:YAG laser in xenon.
• Current methods yield low VUV light efficiency, typically in the nanojoule per pulse range.

Purpose of the Study:

• To describe the fundamental theory and experimental setup for producing 118 nm light.
• To propose and validate a new model explaining the observed decrease in VUV light production at higher xenon pressures.
• To investigate the mechanism limiting VUV light generation based on pressure-broadened absorption.

Main Methods:

• Utilizing frequency tripling of 355 nm laser light in xenon gas to generate 118 nm VUV light.
• Conducting experiments to measure VUV light production at varying xenon pressures.
• Developing a theoretical model incorporating pressure-broadened absorption to explain experimental observations.

Main Results:

• Experimental VUV light production does not follow the simple quadratic pressure dependence predicted by basic models.
• A maximum in 118 nm light production is observed, followed by a decrease to zero with increasing xenon pressure.
• The proposed model based on pressure-broadened absorption successfully explains the experimental findings.

Conclusions:

• Pressure-broadened absorption is identified as the key mechanism limiting 118 nm VUV light production at higher xenon pressures.
• The new model provides a more accurate understanding of VUV generation efficiency in this system.
• This research contributes to optimizing VUV light sources for gas-phase chemical applications.