CIRCE
Photoemission Spectroscopy and Microscopy
CIRCE is a variable polarization soft x-ray beamline dedicated to advanced photoemission experiments. A plane grating monochromator covering the energy range 100 - 2000 eV will be shared between two independent branches with dedicated experimental end-stations: PEEM (photoemission electron microscopy) and NAPP (near ambient pressure photoemission). A couple of deflecting mirrors will direct the beam to one branch or to the other.
Status
Under construction
The installation of most of the mechanical components of the beamline optics took place in October 2009. The mirrors installation inside the chambers took place in September 2010, and the last grating was installed in the monochromator in December 2010.
The PEEM end station is manufactured and is expected to be delivered in March 2011. The NAPP station is in the detailed design phase and could arrive in summer 2011.
First tests with x-rays are expected to take place before mid 2011.
The CIRCE beamline in December 2009.
Status of the CIRCE infrastructure in June 2009.
People involved
Josep Nicolas: Optics
Lucia Aballe: Beamline Scientist
Virginia Pérez-Dieste: Beamline Scientist
Juanfran Moreno: Engineering Technician
Eric Pellegrin: Supervisor soft x-ray beamlines
Antonio Milan: Controls Engineer
Julio Lidón: Electronics Engineer
Open positions:
There are currently no open positions.
Beamline Characteristics
| Photon energy | 100 - 2000 eV |
| Polarization | Variable |
| Energy resolution | ~ 8000 |
| Photon flux | ~ 1013 ph/s |
| Beam spot size at PEEM position (VxH) | variable, min 4 x 30 um2 |
| Beam spot size at PES position (VxH) | ~ 20 x 100 um2 |
Technical Description
Source:
The source for the Circe beamline is a Pure Permanent Magnet APPLE II helical undulator, inserted in the center of the 9th medium straight section of the ALBA storage ring. This device is capable of delivering linearly polarized light, in all the directions, as well as circularly polarized light (left- or right-handed).
Optics:
The Circe beamline has a variable included angle plane grating monochromator. A plane mirror and three diffraction gratings are used to cover the full energy range. After the grating chamber, alternatively one of two toroidal mirrors focus on the exit slit of the PEEM or NAPP branch. The refocussing section consists on a pair of Kirkpatrick Baez mirrors for the PEEM branch and a toroidal mirror for the NAPP branch.
End stations:
Each branch will have a dedicated end station:
PEEM: a high performance photoemission electron microscope with spectroscopic capabilities will be available for advanced surface science and nanostructures studies.
NAPP: an analysis chamber for near ambient pressure photoelectron spectroscopy studies will enable research on chemical reactions, liquid surfaces and other problems unaccessible with UHV setups.
