Fig. 1: Dominance of tunable, narrowband X-rays over bremsstrahlung in bulk van der Waals (vdW) crystals, producing substantial enhancements in X-ray intensity compared to thin films.
From: Enhanced tunable X-rays from bulk crystals driven by table-top free electron energies
a Monte Carlo simulation of 20 keV electrons incident on a 1 mm-thick bulk graphite crystal tilted at 10°. The gray region represents the graphite crystal, while the white area depicts free space. Electrons are emitted above the graphite crystal with an initial kinetic energy of 20 keV. The colored trajectories within both the gray (graphite) and white (free space) regions depict electron scattering paths, with colors indicating the corresponding electron kinetic energies. b Illustration of a similar scenario with a 29 nm-thick graphite thin film. c Tunable X-ray emission from a 1 mm-thick highly oriented pyrolytic graphite (HOPG) bulk crystal, measured under electron energies of 17.5, 20, 22.5, and 25 keV. Solid dots with error bars represent experimental data, while theoretical predictions are shown as solid lines. d Tunable X-ray emission from a 29 nm-thick graphite thin film. Solid dots with error bars represent experimental data, translucent bands indicate variations in theoretical predictions due to uncertainties in the thin film thickness under experimental conditions. The definition of the error bars is provided in the Supplementary Information (SI) Section S3. All spectra correspond to a solid angle of 0.066 steradians, which is in accordance with experimental conditions.
