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The experimental basis of laboratory is two ultrahigh
vacuum multi-chamber setups adapted for surface chemical reactions study.
Now we are also able to perform in situ nanostructures creation
and their study. All technological and measurement processes are controlled
by IBM compatible computers with original software.
As technological tools we use:
- Cooling (by LN2 circulation) and heating (by Ta wire radiation
and electron beam) from 95 to 1600 K
- active gas inlet (by means of piezoceramic leak valve) controlled
by computer with mass-spectrometer back-loop.
- ion bombardment (RIBER CI-10, CI50RB ion guns) for sample preparation
and STM tips sharpening.
As analytical methods we use:
Surface spectroscopic (composition and chemical state measurements)
- SERS (Surface Enhanced Raman Scattering). A Raman spectroscopic apparatus
coupled with an ultra-high vacuum system equipped with typical surface
science measurements, such as LEED, and AES and VT STM. This apparatus
can be used for the vibrational characterization of small metal particles
at surfaces.
- PL (Photoluminescence). Realized on the same spectrometer as SERS.
- AES (Auger Electron Spectroscopy). Standard measurement of surface
composition. We also use Factor Analysis for Auger spectra treatment
permitting to draw the concentration profiles of chemical compositions
along the process on the surface.
- TDS (thermal desorption spectroscopy). This is a classic technique
for obtaining data on surface phases. Can be employed for mass-spectrometry,
AES, and SERS.
- Surface crystallographic (structural measurements at low lateral resolution)
- LEED (Low Energy Electron Diffraction). LEED is a classic surface
crystallographic tool.
- EELFS (Extended Energy Loss Fine Structure). EELFS is based on the
analysis of the energy loss that an electron beam undergoes when exciting
an electronic transition in an atom in a solid. Measurements can be
performed by means of the setup used for AES.
- Local structural probes (structural measurements at atomic scale lateral
resolution)
- STM (Scanning Tunneling Microscopy). A custom built, ultra high vacuum
STM system is available. This system offers excellent performances compared
to existing commercial apparatuses, providing routine atomic resolution
on non metallic systems, and in specific conditions on metallic ones,
such as clean copper or silver. A new STM capable of measurements at
variable temperatures is at presently being assembled.
First setup consists of four chambers: STM chamber,
preparation chamber, main analytical chamber and in-lock chamber (fig.1).
Second setup also consists of four chambers: STM chamber,
STM tip preparation chamber, main analytical chamber and in-lock chamber.
Variable Temperature STM unites with optical spectrometer for SERS and
PL measurements.
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