Photoemission with laser-generated harmonics tunable to 80 eV.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Materials Science
• Quantum Optics

Background:

• High-energy photons are crucial for probing electronic structures.
• Existing methods for generating tunable, high-energy photons face limitations.
• Laser-driven high-harmonic generation (HHG) offers a promising pathway.

Purpose of the Study:

• To demonstrate the generation of broadly tunable harmonic photons up to 80 eV.
• To characterize the properties of these harmonic photons.
• To showcase their application in photoemission spectroscopy.

Main Methods:

• Utilizing a laser system producing 200-fs, 0.5-mJ, 610-nm pulses at 540 Hz.
• Focusing laser light into high-density rare gas atoms generated by a pulsed valve.
• Employing a grazing incidence toroidal grating for wavelength selection.
• Refocusing selected photons onto samples in a vacuum analysis chamber.

Main Results:

• Successfully generated tunable harmonic photons with energies up to 80 eV.
• Demonstrated wavelength selection using a toroidal grating.
• Obtained valence and atomic core-level photoemission spectra using the generated photons.

Conclusions:

• The developed system provides a versatile source of high-energy, tunable photons.
• This technique is effective for high-resolution photoemission spectroscopy.
• Opens new avenues for studying electronic properties of materials.