Dynamic screening probed by core-resonant double photoemission from surfaces

Area of Science:

• Atomic and Molecular Physics
• Surface Science
• Quantum Dynamics

Background:

• Core hole creation is a fundamental process in atomic and molecular physics.
• Understanding the ultrafast dynamics of core holes is crucial for various fields.
• Previous experimental evidence for attosecond core hole response has been lacking.

Purpose of the Study:

• To experimentally demonstrate the attosecond time scale response of a sudden core hole.
• To investigate the energy sharing dynamics between photoelectrons and Auger electrons.
• To identify shakeup induced interband transitions on the Ag(100) surface.

Main Methods:

• Utilized a two-dimensional coincidence spectrometer for high-resolution measurements.
• Analyzed the energy sharing between Ag 4p photoelectrons and N2,3VV Auger electrons.
• Compared coincidence spectra with M4,5VV Auger transitions to identify surface effects.

Main Results:

• Demonstrated extensive energy sharing (>10 eV) between Ag 4p photoelectrons and N2,3VV Auger electrons.
• This energy width provides access to the attosecond time scale of the emission process.
• Identified the dynamic fluctuation process 4p(-1)⇌4d(-2)4f as the fingerprint of core hole response.
• Observed shakeup induced interband transitions from the Ag(100) surface.

Conclusions:

• Provided the first experimental demonstration of the universal attosecond time scale response of a sudden core hole.
• Established a method to probe ultrafast electronic dynamics via electron-electron interactions.
• The findings offer insights into electron correlation and surface phenomena in metals.