Raman Laser Microprobe Microscopy

XRD, X-ray diffraction XRF, X-ray fluorescence AAS, atomic absorption spectrometry ICP-AES, inductively coupled plasma-atomic emission spectrometry ICP-MS, Inductively coupled plasma/mass spectroscopy IC, ion chromatography EPMA, electron probe microanalysis SEM, scanning electron microscope ESEM, environmental scanning electron microscope HRTEM, high-resolution transmission electron microscopy LAMMA, laser microprobe mass analysis XPS, X-ray photo-electron spectroscopy RLMP, Raman laser microprobe analysis SHRIMP, sensitive high resolution ion microprobe. PIXE, proton-induced X-ray emission FTIR, Fourier transform infrared. 

Fourier transform infrared (FTIR) and Raman laser microprobe (RLMP) microscopy... 

Infrared and ultraviolet probes for surface analysis are then considered.The applications of IR spectroscopy and Raman microscopy are discussed, and a brief account is also given of laser-microprobe mass spectrometry (LAMMA). 

Characterization thus involves analytical electron microscopy, ordinary microprobe analysis or other techniques for localizing elements or chemical compounds (Scanning Auger Spectroscopy, Raman Microprobe, Laser Microprobe Mass Spectrometry). It also requires, in most cases, some physical separation of the catalyst for separate analysis (e.g., near surface parts and center of pellets, by peeling or progressive abrasion pellets present at various heights in the catalyst bed, etc.). 

Although a combination of spectroscopy imaging e.g. /xXRF, /xFTIR, /xRS) would offer a powerful way to characterise materials various hurdles must be overcome to achieve the ultimate in integrated spectroscopic imaging. These difficulties include spatial resolution, specimen preparation, spectroscopic probe penetration depth and image integration. Same-spot (optical, /u-FTIR, /u.RS) technology is now available. The topic of Raman microscopy in combination with other microanalysis techniques (electron microscopy/X-ray microanalysis ion mi-croprobe mass spectrometry, and laser microprobe mass spectrometry), i.e. dual-use microprobe systems, has been discussed [534]. 

Aerosol Heterogeneity. The variation of the chemical composition from particle to particle within an aerosol size class has been probed in a number of ways. Single-particle chemical analysis has been achieved by using the laser Raman microprobe (25) and analytical scanning electron microscopy (26). With the electron microscope techniques, the particle can be sized as well as analyzed chemically, so the need for classification prior to sample collection is reduced. Analyzing hundreds to thousands of particles provides the information necessary to track the particles back to their different sources but is extremely time consuming. 

The surface morphology, thickness and quality of the deposited carbon films are analyzed by scanning electron microscopy (SEM), by energy dispersive x-ray (EDx) and by Raman spectroscopy (RS). The Raman spectrum was recorded using an argon ion laser Raman microprobe. The exciting laser wavelength is 632.81 nm with a laser power equal to 1.75 mW. The instrument was operated in the multi-channel mode with the beam focused to a spot diameter of approximately 2 pm. 

An important development in Raman spectroscopy has been the coupling cf the spectrometer to an optical microscope. This allows the chemical and structural analysis described above to be applied to sample volumes only 1 across [38]. No more sample preparation is required than that for optical microscopy, and the microscope itself can be used to locate and record the area which is analyzed. This has obvious practical application to the characterization of small impurities or dispersed phases in polymer samples. This instrument, which may be called the micro-Raman spectrometer, the Raman microprobe or the Molecular Optics Laser Examiner [39] has also been applied to the study of mechanical properties in polymer fibers and composites. It can act as a non-invasive strain gauge with 1 fim resolution, and this type of work has recently been reviewed by Meier and Kip [40]. Even if the sample is large and homogeneous, there may be advantages in using the micro-Raman instrument. The microscope... 

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