Design of a compact, high-resolution velocity-map imaging spectrometer for attosecond spectroscopy

Area of Science:

• Atomic, Molecular, and Optical Physics
• Ultrafast Science
• Spectroscopy

Background:

• Velocity Map Imaging (VMI) spectrometers are crucial for studying electron and ion dynamics.
• Optimizing VMI spectrometers is essential for achieving higher spectral resolution in ultrafast spectroscopy.
• Previous VMI designs have limitations in spectral resolution and response across broad energy ranges.

Purpose of the Study:

• To design and optimize a compact VMI spectrometer for attosecond spectroscopy.
• To improve spectral resolution by a factor of approximately 5 compared to existing designs.
• To ensure a flat spectral response in the 10-40 eV energy range.

Main Methods:

• Utilized numerical simulations to optimize the lens shape, size, and material of a compact three-electrode VMI configuration.
• Employed an attosecond source based on high-order harmonic generation for experimental testing.
• Compared experimental measurements with simulated spectral resolution.

Main Results:

• Achieved a spectral resolution improvement of approximately 5x relative to the initial design.
• Demonstrated a flat spectral response within the 10-40 eV energy range.
• Observed good agreement between measured and simulated spectral resolution.

Conclusions:

• The optimized VMI spectrometer design significantly enhances spectral resolution for attosecond spectroscopy.
• The electrostatic lens is a limiting factor at low kinetic energies, while camera objective resolution impacts the high energy range.
• This improved VMI spectrometer is well-suited for detailed investigations of ultrafast electron dynamics.