Femtosecond high-resolution hard X-ray spectroscopy using reflection zone plates

Area of Science:

• X-ray optics and spectroscopy
• Synchrotron radiation applications
• Materials science instrumentation

Background:

• Wavelength-dispersive X-ray spectrometry (WDS) is crucial for elemental analysis.
• Existing energy-dispersive instruments have limitations in the 7.8-9.0 keV range.
• Ultra-fast hard X-ray spectroscopy demands high temporal and spectral resolution.

Purpose of the Study:

• To introduce and evaluate an off-axis total external reflection zone plate for WDS.
• To assess the performance of this new optic in the hard X-ray spectral range.
• To explore its potential for ultra-fast spectroscopy at free-electron lasers (FELs).

Main Methods:

• Application of an off-axis total external reflection zone plate in WDS.
• Proof-of-concept experiment conducted at a synchrotron facility.
• Measurement of resolving power (E/ΔE) and detection efficiency.
• Characterization of temporal pulse elongation.

Main Results:

• Achieved a resolving power (E/ΔE) of up to 1.1 × 10^2 in the 7.8-9.0 keV range.
• Demonstrated a detection efficiency of (2.2 ± 0.6)%, with a constant count rate.
• Observed minimal temporal pulse elongation (≤ 1.5 × 10^-15 s).
• Performance comparable to existing energy-dispersive instruments.

Conclusions:

• The off-axis zone plate is a viable optic for high-performance WDS.
• The technology enables ultra-fast hard X-ray spectroscopy with excellent spectral resolution.
• This advancement is particularly promising for applications at free-electron lasers (FELs).