Highly angular resolved X-ray photoelectron diffraction measurements by using the diffraction plane aperture

We have been carrying out a X-ray Photoelectron Diffraction (XPED) measurements by using a new input-lens-system and a high power X-ray source. In the new input-lens-system, high angle resolution and high throughput are accomplished by placing an aperture not on the image plane but on the diffraction plane of electron optics. The focal position on the diffraction plane has a linear relationship to the emission angle and is independent of kinetic energy. The angular resolution is numerically obtained as a function of the aperture size. A high angular resolution is therefore easily achieved with a small aperture. In the angle-resolving lens system, aperture sizes (Φ4 mm, Φ2 mm, Φ00.5 mm, Φ00.25 mm) correspond to the angular resolutions (±0.6°, ±0.3°, ±0.08°, ±0.04°) respectively. High angle-resolved XPED patterns from Ge(111) are obtained. Detected photoelectron intensities are high enough to measure the PED pattern even if angle resolution is 0.04°. Moreover, fine structure of the PED pattern such as the Kikuchi pattern can be measured clearly.