BL25SU Photoemission Spectrometer (PES)
Inquiry number
INS-0000000345
High-resolution photoemission spectroscopy (PES) is a means of directly probing electronic states in solids. At BL25SU, the high-resolution PES is possible at excitation energies in the range of 220 to 1500 eV. At low excitation energies (≤120 eV) conventionally used for the high resolution PES, PES is a surface sensitive technique because of short photoelectron mean free paths (≤5 Å). However at high excitation energies (~ 1 keV), the mean free paths become as long as 15 Å. This enables us to probe bulk electronic states in solids. The system consists of a GAMMADATA-SCIENTA SES200 spectrometer combined with a varied line-spacing plane grating monochromator. Angle-resolved PES in the soft X-ray range can also be performed using this system, which provides band dispersions of bulk electronic states.
| Excitation energy | 220 ∼ 1500 eV |
| Total energy resolution | ∼ 100 meV at ∼ 1 keV |
| Angular resolution | ∼ 0.2° |
| Detection angle | ± 6° |
| Spot size | ∼ 0.1 × 0.1 mm2 |
| Sample temperature | 20 ∼ 300 K |
A Schematic view of experimental setup
Typical data
High-resolution Ce 4f spectra in the 3d-4f (resolution, 100 meV) and 4d-4f (resolution, 50 meV) resonances of CeRu2Si2 and CeRu2. The line shapes of the 4d-4f RPES are mutually similar, but those of the 3d-4f RPES are drastically different each other. The different 3d-4f RPES spectral weight are reflecting the substantial bulk 4f states of the compounds, which have not been revealed by the "surface-sensitive" 4d-4f RPES.
References
- A. Sekiyama et al., Nature 403, 396 (2000).