The characteristics and purposes of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy (XAS), photoemission spectroscopy (PES) and infrared spectroscopy (IR), are described as follows:
X-ray Absorption Spectroscopy
X-ray Absorption Spectroscopy is typically
divided into two regimes: the X-ray absorption near-edge structure (XANES) and
the extended X-ray absorption fine structure (EXAFS) spectroscopy. XANES is
strongly sensitive to oxidation state and coordination chemistry of the
absorbing atom, while EXAFS is used to determine the bond length, coordination
number, and species of the neighbors of the absorbing atom. Samples may be
crystalline or amorphous, and in nearly any form (solid, liquid, gas, solution,
mixture, etc.), and may be measured in situ under a variety of conditions.
Photoemission Spectroscopy
Photoemission Spectroscopy is a surface chemical
and physical analysis techniques that can be used to measure the elemental
composition, empirical formula, chemical state and electronic state of the
elements that exist within a material. Using synchrotron radiation as the light
source can provide many advantages, such as the tunability over a wide
frequency range, high brilliance and polarization.
Infrared Spectroscopy
Infrared Spectroscopy is the absorption
measurement of different IR frequencies by a sample positioned in the path of
an IR beam. The main goal of IR spectroscopic analysis is to determine the
chemical functional groups in the sample. The higher-energy near-IR can excite
overtone or harmonic vibrations. The mid-infrared may be used to study the
fundamental vibrations and associated rotational-vibrational structure. The
far-infrared, lying adjacent to the microwave region, has low energy and may be
used for rotational spectroscopy. Synchrotron radiation based IR
microspectroscopy can not only provide considerable brightness advantages over
conventional IR sources but also greatly improve the spatial resolution.