▼Description
BL2A is a soft X-ray beamline for photoabsorption spectroscopy. The beamline is equipped with a focusing premirror and a double-crystal monochromator [1]. The monochromator serves soft X-rays in the energy region from 585 to 4000 eV using several types of single crystals, such as beryl, KTP (KTiOPO4), InSb, and Ge. The throughput spectra measured using a Si photodiode (AXUV-100, IRD Inc.) are shown in Fig. 1. The typical energy resolution (E / ΔE) of the monochromator is approximately 1500 for beryl and InSb.
There is a small vacuum chamber equipped with an electron multiplier (EM) detector. Photoabsorption spectra for powdery samples are usually measured in total electron yield mode, with the use of the EM detector. In addition, a hemispherical electron analyzer for photoelectron spectroscopy is equipped.
Recently, a new omnidirectional photoelectron acceptance lens (OPAL) has been developed aiming to realize 2π-steradian photoelectron spectroscopy and photoelectron holography [2]. As shown in Fig. 2, by combining OPAL and the existing hemispherical electron analyzer, a photoelectron spectrometer with high energy resolution can be realized, and a full range (±90゜) 1D angular distribution can be measured at once. This upgrade is currently in the commissioning phase.
| Fig. 1. Throughput spectra of the double-crystal monochromator at BL2A. | Fig. 2. Side view of BL2A. |
▼Technical Data
| Monochromator | Double crystal monochromator |
| Monochromator crystals: (2d value, energy range) |
beryl (15.965 A, 826-2271 eV),
KTP (10.95 A, 1205-3310 eV), InSb (7.481 A, 1764-4000 eV), Ge (6.532 A, 2094-4000 eV) |
| Resolution | E/ΔE = 1500 for beryl and InSb |
| Experiments | Photoabsorption spectroscopy (total electron yield using EM and partial fluorescence yield using SDD) |
