BL25SU Photoemission Electron Microscope (PEEM)
Inquiry number
INS-0000000344
The photoelectron emission microscopy (PEEM) station of BL25SU is aimed at investigations of magnetic and electronic properties with nano and submicro spatial scales. A bolt-on-type electrostatic photoelectron microscope is employed. In combination with the helicity switching of circularly polarized soft x-rays, high-precision imaging of magnetic domain structures is performed by utilizing magnetic circular dichroism (MCD) effects. Sample preparations and characterizations can be made in situ. The simple operation system of this station opens opportunities even for non-specialists of PEEM experiments.
The system consists of three chambers: load lock, preparation, and PEEM measurement chambers. The measurement chamber is equipped with a PEEMSPECTOR (Elmitec GmbH) and a 5-axes sample manipulator with a liquid nitrogen cryostat and an electron-bombardment heating system. The spatial resolution of the PEEMSPECTOR is estimated at less than 35 nm using a Hg discharge lamp. Working resolutions in the case using soft x-ray synchrotron radiation could be somewhat worse due to chromatic aberrations. Circularly-polarized soft x-rays are injected to a sample surface at an angle of about 60° from the surface normal. The azimuthal angle of a sample can be varied from 0 to 360° and tilt angles are adjustable around two axes perpendicular to each other. The traveling lengths of a sample are ± 3 mm along x and y directions, and ± 15 mm along z direction, respectively. The sample temperature can be controlled from 160 to 1600 K. PEEM images are recorded by a Peltier-cooling CCD camera (SensiCam, PCO AG) with a 12-bit dynamic range, 1376 × 1040 pixels, quantum efficiency ≥ 60%, and exposure times from 1 ms to 10000 s. As for MCD measurements, PEEM images are recorded in synchronization with the periodical helicity switching. The frequencies of helicity switching are selective between 0.1- and 1 Hz, which are chosen so as to give the better quarity of PEEM image. A Hg discharge lamp is also available for off-line PEEM observations. The preparation chamber is equipped with an E-gun-type evaporator, a quartz-microbalance thickness monitor, a RHEED system, an ion gun, and a sample heating stage. The whole system is mounted on an x-y-z adjustable stage with an air damper.
| Photon energy range | 220 ~2000 eV |
| Spatial resolution (with Hg lamp) | 35 nm |
| Field of view | 5, 10, 25, 50, 100, 500 µm |
| Sample temperature | 160 ~1600 K |
Fig. 1 Front and side views of the PEEM station
Fig. 2 A PEEM image of Co micro dots.