Single bunch X-ray pulses on demand from a multi-bunch synchrotron radiation source.

Area of Science:

• Physics
• Materials Science
• Spectroscopy

Background:

• Synchrotron radiation facilities typically operate in multi-bunch mode.
• Time-of-flight (TOF) based applications necessitate single bunch operation for precise timing.

Purpose of the Study:

• To develop a method for generating a distinct single bunch soft X-ray source from a multi-bunch synchrotron beam.
• To enable advanced time-resolved photoemission spectroscopy (TR-PES) using synchrotron light.

Main Methods:

• Utilizing quasi-resonant excitation of incoherent betatron oscillations in a storage ring.
• Implementing a pulse picking scheme for horizontal pulse separation.
• Employing a new generation of angularly resolving electron spectrometers.

Main Results:

• A separable single bunch soft X-ray source was created alongside multi-bunch operation.
• The source offers variable polarization (linear and circular) and high photon flux (10^7-10^9 ph/s/0.1%BW).
• Achieved pulse purity of 10^4-10^2 and repetition rate of 1.25 MHz with pulse durations of 30 ps or 2-3 ps.

Conclusions:

• The developed pulse picking scheme successfully generates a high-quality single bunch soft X-ray source.
• This method provides unique opportunities for time-resolved photoemission studies, particularly in surface physics.
• The technique is well-suited for diffraction-limited light sources, promising ultimate spectral resolution.