Spectroscopy synchrotron techniques

Sciences de TUnivers. His research interests focus on environmental mineralogy and biogeochemistry of metal contaminants and trace elements using X-ray structural techniques. In the mid-80s, he initiated a new research program on the structure and surface reactivity of poorly crystallized Fe oxides. In the early 90s, this program was extended to Mn oxides, and specifically to minerals of the bimessite family. In the mid-90s, he pioneered the application of synchrotron techniques to determination of the speciation of heavy metals in natural systems. In the last two years, he was a key developer of an X-ray microprobe at the Advanced Light Source of the Lawrence Berkeley National Laboratory dedicated to the study of complex environmental materials. He is also co-lead PI of the French Absorption spectroscopy beamline in Material and Environmental sciences (FAME) at the European Synchrotron Radiation Facility (ESRF) in Grenoble. 

A better understanding of NNSM-induced morphological changes has been initiated by employing synchrotron-based infrared micro-spectroscopy. In this recent study [17], authors have chosen three common semi-crystalline and amorphous polymers for blending Hydrophobic polymers polystyrene (PS), polyethylene terephthalate (PET), and poly(methyl-methacrylate) (PMMA) labelled hereafter PS/PET and PET/PMMA. The results of such studies clearly show the potential of the synchrotron technique to detect the transition region between the two polymers, and provide evidence for the fluctuations in blend concentration for PS/PMMA. 

In addition to using X-rays to irradiate a surface, ultraviolet light may be used as the source for photoelectron spectroscopy. This technique, known as ultraviolet photoelectron spectroscopy (UPS, Figure 7.39), is usually carried out using two He lines (Hel at 21.2 eV and Hell at 40.8 eV), or a synchrotron source. This... 

IR spectroscopy is a valuable complementary technique to Raman spectroscopy. Synchrotron based IR micro-spectroscopy is a new technique that shows promising perspectives for studies of skin and human cells (28). At the Max-Lab synchrotron beam line in Lund, Sweden an IR microscope is now being installed (29). This instrument will allow IR-spectra to be recorded with a bolometer detector down to 50 cm (around 1,5 THz). In the R(v)-representation of the low-wavenumber Raman spectrum it is very difficult to quantify the amount of free water because the water band at 180 cm is weak compared to the protein hydrogen bond band at 110-120 cm" Hopefully the water band is relatively more intense in the IR spectrum allowing a detection of the free water at low concentrations. 

Eland, J. H. D. (1983) Photoelectron Spectroscopy. 2nd edn, Butterworth-Heinemann, London. Huffier, S. (2001) Photoelectron Spectroscopy Principles and Applications. 3rd edn. Springer, Berlin. Prince, K. C. (1995) Photoelectron Spectroscopy of Solids and Suifaces Synchrotron Radiation Techniques and Applications, World Scientific Publishing, Singapore. 

X-ray absorption spectroscopy is an important part of the armory of techniques for examining pure and applied problems in surface physics and chemistry. The basic physical principles are well understood, and the experimental methods and data analysis have advanced to sophisticated levels, allowing difficult problems to be solved. For some scientists the inconvenience of having to visit synchrotron radia-... 

Other techniques utilize various types of radiation for the investigation of polymer surfaces (Fig. 2). X-ray photoelectron spectroscopy (XPS) has been known in surface analysis for approximately 23 years and is widely applied for the analysis of the chemical composition of polymer surfaces. It is more commonly referred to as electron spectroscopy for chemical analysis (ESCA) [22]. It is a very widespread technique for surface analysis since a wide range of information can be obtained. The surface is exposed to monochromatic X-rays from e.g. a rotating anode generator or a synchrotron source and the energy spectrum of electrons emitted... 

The major advantage of time-resolved X-ray techniques, as compared to optical spectroscopy, is that their wavelength X as well as the pulse duration r can be chosen to fit the atomic scales. This is not the case for optical spectroscopy, where the wavelength X exceeds interatomic distances by three orders of magnitude at least. Unfortunately, X-ray techniques also have their drawbacks. They require large-scale instruments such as the synchrotron. Even much larger... 

An interesting feature of polarized IR spectroscopy is that rapid measurements can be performed while preserving molecular information (in contrast with birefringence) and without the need for a synchrotron source (X-ray diffraction). Time-resolved IRLD studies are almost exclusively realized in transmission because of its compatibility with various types of tensile testing devices. In the simplest implementation, p- and s-polarized spectra are sequentially acquired while the sample is deformed and/or relaxing. The time resolution is generally limited to several seconds per spectrum by the acquisition time of two spectra and by the speed at which the polarizer can be rotated. Siesler et al. have used such a rheo-optical technique to study the dynamics of multiple polymers and copolymers [40]. 

The most prevalent technique exploiting synchrotron radiation is X-ray absorption spectroscopy (XAS, also called X-ray absorption fine structure, XAFS). Two related types of experiments are conducted X-ray absorption near-edge spectroscopy (XANES), which probes the initial absorption edge and related nearby structure, and... 

---