Micro-Raman strain

The vast identification potential of micro-Raman spectroscopy combined with the aforementioned sophisticated chemometric analysis methods is corroborated within various works In one study a total of 2257 Raman spectra of single cells were used to differentiate among 20 strains belonging to 9 different species. Here, a recognition rate of 89.2% for strains using the SVM technique could be achieved, albeit these bacteria were grown under different conditions (cultivation time medium, and temperature). [45]... 

Fig. 19.3. Representative micro-Raman spectra of single bacterial cells belonging to different species and strains that are predominantly present in pharmaceutical production in case of microbial contamination...

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... 

In this section, we examine the internal stress within the cotton fibers treated with SMPU and DMDHEU. Eichhom and Young (Eichhom et al, 2001 Eichhom and Yoimg, 2001,2003 Eichhom eta/., 2003) showed that the internal stress of cellulose fibers can be measured by shifts of C-O-C vibrations in the Raman spectrum an increase in the wave intensity indicates a reduction of the internal stress, and vice versa. Using the strain-induced shift in the special Raman peak, incorporated with micro-Raman spectroscopy, is a technique unique to micro-mechanics. A Raman spectrum of imtreated cotton is shown in Fig. 10.15. The C-O-C peaks are 1096 and 960cm , depending on the internal stress of the cellulose chain. 

Wright of Advanced Micro Devices discusses the use of Raman microspectroscopy to measure the integrity of a film on semiconductor wafers during manufacture in US patent 6,509,201 and combined the results with other data for feed-forward process control [181]. Yield is improved by providing a tailored repair for each part. Hitachi has filed a Japanese patent application disclosing the use of Raman spectroscopy to determine the strain in silicon semiconductor substrates to aid manufacturing [182]. Raman spectroscopy has a well established place in the semiconductor industry for this and other applications [183]. 

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