BL25SU Photoemission Spectrometer (PES)
Inquiry number
INS-0000000345
This station is dedicated to photoemission spectroscopy (PES) of solid samples under UHV conditions. The excitation light is soft x-rays supplied from the A-branch of BL25SU. A DA30 analyzer of Scienta Omicron GmbH is used. The electron lens of this hemispherical analyzer has a deflector, which enables two dimensional angular distribution measurements. The acceptance angle is ±15° and the deflectable range is ±10°. The incident angle of the beam with respect to the sample surface is set at a grazing angle ≤ 5° to maximize the photoemission intensity. The spot size on the sample under the grazing condition is typically ~50 µm × ~150 µm. The best-focused spot size on the sample is 30 µm × 80 µm when the incident angle is 5°. The following methods are often used at this station. Advantages of each method and available conditions are listed.
(1) Angle resolved photoemission spectroscopy (ARPES)
• Measurements of band dispersions or Fermi surfaces.
• Bulk sensitive compared to ARPES using VUV.
• Fermi surfaces can be measured without sample rotation owing to the deflector equipped analyzer.
• Base pressure: < 5×10-8 Pa
• Sample temperature: 10 K - 300 K.
• Sample preparation: cleaving.
(2) Photoelectron diffraction or photoelectron holography
• Structural analysis of local atomic arrangements.
• Chemically shifted core levels can be selected by the high energy resolution analyzer.
• Azimuth- and polar- angle rotations are available keeping the incident beam angle of 5°.
• Base pressure: < 5×10-8 Pa
• Sample temperature: R. T.
• Sample preparation: ion bombardment and annealing up to ~1300 K.
(3) X-ray photoemission spectroscopy (XPS)
• Angle-resolved XPS is available in addition to angle-integrated XPS
• Base pressure: < 5×10-8 Pa
• Sample temperature: 10 K - 300 K.
Fig. 1 Photo of the PES station.