Ultra Angle Resolved Photoelectron Spectroscopy
UARPES beamline at Solaris Synchrotron in Krakow
The Ultra Angle Resolved Photoelectron Spectroscopy (UARPES) beamline is an experimental installation for studies of the electronic band structure of solid surfaces. The beamline is designed for the energy range 8 – 100 eV, providing high photon flux, high resolution, and variable polarization, with minimalized harmonic contamination. Elliptically polarizing, APPLE-II type undulator is a radiation source. The undulator has a quasi-periodic geometry to suppress unwanted harmonics. The beamline monochromator combines normal (NIM) and grazing incidence (PGM) optics. The experimental end-station is composed of several ultrahigh vacuum chambers for sample processing and analysis, as well as devices for sample storage and transfer. Cryogenic, 5-axes manipulator is capable of stabilizing the sample temperature in wide range, as well as of precise positioning of the sample surface for experiments. State-of-the-art electron energy spectrometer VG SCIENTA DA 30L is capable of massively parallel recording of angle-resolved spectroscopic data. Low energy electron diffractometer (LEED), with an image amplifier, is available for a precise sample orientation and for surface structure studies. The set-up allows for in situ sample processing techniques such as: sputter cleaning, thermal annealing, sample cleaving. Users may insert their own devices allowing for thin film growth or surface reactions in the gas phase. Sample surface composition and crystallographic order may be monitored in situ during preparation processes using combined LEED/AES device.
|Source||Elliptically polarizing undulator APPLE II type, quasiperiodic. 21 magnetic periods, period length: 120 mm|
|Photon energy range||NIM: 8 eV–30 eV, PGM: 16 eV–100 eV|
|Polarization||Linear vertical, linear horizontal, circular, eliptical ,linear skewed. For the linear skewed polarisation the theoretical low energy limit is 12 eV|
|Resolving power (RP)||20 000|
|Beam size at the sample (HxV)||NIM: 350 μm x 60 μm, PGM: 270 μm x 30 μm|
|Photon flux at the sample||> 5 x 1011 photons/s @ 20 000 RP|
|Sample temperature during measurements||8–500 K|
|Electron spectrometer energy max. resolution||1.8 meV|
|Available sample preparation techniques||Cleaving, thermal annealing up to 1700 K, sputtering, thin film growth|
The UARPES end-station includes a load-lock for fast sample transfer from air into the ultrahigh vacuum (UHV) environment, a preparation chamber, a sample magazine for 12 samples, the main analysis chamber. The preparation chamber includes LEED/Auger device for surface structure and composition monitoring, an ion gun, and ports for several user devices. When planning your experiment please be aware that:
- Samples must be solid, UHV compatible, flat and should not charge under UV illumination.
- Samples must fit a “Omicron type plate” sample holder (Ta and Ti holders are available)
- Heating may be done with thermal radiation (up to 1100 K) or with electron beam (up to 1700 K ). For the highest temperatures the Ta holder with an orifice has to be used.
- The sample mounting is possible using Ta clamps welded to the Ta holder. Samples that are not rigid enough or too small may be also glued on an epotec glue. Heating in vacuum will be unavailabe for such samples.
- Sample orientation for the studies is possible using two rotation axis. The azimutal rotation is not available in situ. If azimutal orientation of the sample is important it has to be done prior to insertion of the sample into the system. At present Solaris does not offer access to an X-ray device for preorientation of crystals.
- Number of samples that can be inserted into a system at single pumping cycle: 6
- Number of user samples that can be stored in UHV: 10
- Experimental plans have to be discussed in detail with the beamline staff.
Detailed information can be found on the beamline’s main page.
The UARPES beamline is still under commissioning and we can not guarantee all beam parameters to stay close to the theoretical ones during experiments.
X-ray Absorption Spectroscopy