Determine the physical origin of photoelectron energy offsets caused by helium nanodroplets

Determine the exact physical origin of the relative photoelectron energy offsets observed when helium nanodroplets are present near the entrance of the hemispherical electron analyzer.

Background

The photoelectron kinetic-energy scale was calibrated using gas-phase krypton 3d spectra. Small relative energy offsets were observed between sequential foreground measurements with the helium-nanodroplet beam present and background measurements with the beam blocked. Because the offsets affected gas-phase atomic lines and were not consistently identical, the authors attributed them to a general experimental perturbation rather than to dopant-specific binding-energy shifts, but the underlying mechanism remains unresolved.

References

The presence of HNDs near the entrance of the electrostatic lens of the HEA appears to influence the electron energy measurement; however, the exact physical origin of the energy offsets could not be determined.

— X-ray photoelectron spectroscopy of Ar and Kr clusters formed in He nanodroplets  (2609.04553 - Blaj et al., 3 Sep 2026) in Section Experimental setup, paragraph describing kinetic-energy calibration and foreground/background energy offsets