TASC National Laboratory
Area Science Park - Basovizza S.S. 14, Km 163.5 - 34012 Trieste, Italy
BACH - Beamline for Advanced diCHroism
BACH has been designed to deliver a photon beam with high intensity and
brilliance in the soft x-rays energy range (35 - 1600 eV) with the full
control of the polarization of the light. The goal of this project is the
realization of electronic and photon spectroscopy experiments with
polarization dependence. The following techniques are implemented: XPS
(X-ray
Photoelectron
Spectroscopy),
UPS
(Ultraviolet
Photoelectron
Spectroscopy) , XAS (X-ray Absorption Spectroscopy), XMCD (X-ray
Magnetic Circular Dichroism), XMLD (X-ray Magnetic Linear Dichroism),
SXES (Soft X-ray Emission Spectroscopy), RIXS (Resonant Inelastic X-ray
Spectroscopy).
The radiation source is based on two APPLE-II elliptical undulators that are
used alternatively in order to optimize the flux. The photons dispersion
system is based on the Padmore VASGM (Variable Angle Spherical Grating
Monochromator) scheme and it includes four different interchangeable spherical gratings.
The first three gratings guarantee resolving powers of 20000-6000, 20000-6000 and
15000-5000 in the energy ranges 35-200 eV, 200-500 eV and 500-1600 eV respectively.
Two separate branches, following the monochromator, allow setting two independent
experimental chambers. The flux on the experimental samples, calculated at the best
resolutions achievable, is expected to be above 10 11 photons/s with linearly or circularly
polarized light. In addition a fourth grating operates in the 400-1600 eV range providing
higher flux (1012 photons/s) with smaller resolving power (10000-2000), allowing
fluorescence and x-ray scattering experiments.
The two refocusing sections, based on plane elliptical mirrors in a Kirkpatrick - Baez
configuration, provide nearly aberration free spots on the samples. The dimensions are
200x15 mm2 (Horizontal x Vertical) and 300x30 mm2, respectively. A third branch line
after the monochromator will host a microscope based on Fresnel Zone Plate focusing.
With a spatial resolution of 50 nm, an energy resolution of 30000-2000 in the 40-1500
eV range and a photon flux of 108 photons/s, this instrument will be devoted to
spectromicroscopy at variable polarization, experiments on magnetic domains and
oriented polymer materials, applications in biology and colloid physics.
Contacts:
BACH - Beamline for Advanced diCHroism - Prof. Fulvio Parmigiani
e-mail fulvio@dmf.bs.unicatt.it
tel +39 040 375 8428
fax +39 040 375 8400