Raman microprobe purpose

A principal advantage of the Raman microprobe is that the optics are those of a conventional light microscope a wide variety of special-purpose objectives developed for materials and biological microscopy are available. The Raman microprobe also offers the advantage of fluorescence reduction owing to the high spatial resolution of the microscope if a region of low fluorescence can be chosen for observation. 

Physical and chemical characterization methods are essential to assess aspects such as material and processing quality. Raman microprobe is an analytical tool coupled to an optical microscope. Elemental analysis using the x-rays emitted from the specimens in the electronic microscopy techniques can be used for local composition determination or to obtain a map of the distribution of a certain element in a wider area wavelength and energy-dispersive x-ray spectrometers are used for these purposes. Fourier transform infrared spectrometer is widely used for the qualitative and quantitative analysis of adhesives, the identification of unknown chemical compounds, and the characterization of chemical reactions. Thermal methods such as thermomechanical analysis and differential scanning calorimetry are discussed as valuable tools for obtaining information during postfracture analysis of adhesively bonded joints. 

Raman spectroscopy has been successfully applied to the investigation of oxidic catalysts. According to Wachs, the number of Raman publications rose to about 80-100 per year at the end of the nineties, with typically two thirds of the papers devoted to oxides [41]. Raman spectroscopy provides insight into the structure of oxides, their crystallinity, the coordination of metal oxide sites, and even the spatial distribution of phases through a sample when the technique is used in microprobe mode. As the frequencies of metal-oxygen vibrations found in a lattice are typically between a few hundred and 1000 cm 1 and are thus difficult to investigate in infrared, Raman spectroscopy is clearly the indicated technique for this purpose. 

At this juncture, it is necessary to define what will be considered under the title of process Raman spectroscopy in the industrial environment. Quality assurance/quality control (QA/QC) applications and failure analysis are important areas of industrial interest however, these areas, in general, can be adequately addressed with standard laboratory Raman spectrometers including FT-Raman spectrometers and dispersive microprobes. For the purpose of the remainder of this chapter, the industrial environment and the process Raman analyzer will be restricted to instrumentation and protocols usable for on-line measurements. At this point, it is necessary to outline a definition of what the requirements for an on-line process Raman analyzer are. A process Raman analyzer should be composed of components which have the following properties ... 

---