Raman techniques sampling rate

This article provides some general remarks on detection requirements for FIA and related techniques and outlines the basic features of the most commonly used detection principles, including optical methods (namely, ultraviolet (UV)-visible spectrophotometry, spectrofluorimetry, chemiluminescence (CL), infrared (IR) spectroscopy, and atomic absorption/emission spectrometry) and electrochemical techniques such as potentiometry, amperometry, voltammetry, and stripping analysis methods. Very few flowing stream applications involve other detection techniques. In this respect, measurement of physical properties such as the refractive index, surface tension, and optical rotation, as well as the a-, //-, or y-emission of radionuclides, should be underlined. Piezoelectric quartz crystal detectors, thermal lens spectroscopy, photoacoustic spectroscopy, surface-enhanced Raman spectroscopy, and conductometric detection have also been coupled to flow systems, with notable advantages in terms of automation, precision, and sampling rate in comparison with the manual counterparts. 

As with VCD, the first ROA instruments were built around single-channel scanning dispersive spectrometers [18,19,76,77], Photomultipliers with dualchannel photon-counting electronics were used to record the spectra. Scanning rates were no faster than 1 cm l per minute because of the requirement to accumulate at least 10 7 counts per spectral location, and preferably 10 . Applications with these instruments were limited to samples with favorable Raman scattering and the goals of these early studies were simply to explore the nature of ROA spectra and to improve measurement techniques. Several reviews... 

The chapter thus far has addressed fiber-optic sampling techniques and hardware, illustrated with a few applications. As noted earlier, there has been a wide range of fiber-optic Raman applications presented in the literature, and new reports continue to appear at an accelerating rate. Table 12.4 lists some examples of applications to illustrate the wide variety and breadth of fiberoptic samples. The list is by no means comprehensive, but it should provide the reader with a starting point to explore applications in particular areas. 

Samples were compression molded and slow cooled in air tensile properties were determined at a draw rate of 25.4mmmin percent crystallinity was determined by DSC at a heating rate of 10°Cmin crystal phase structures were determined by Raman internal mode technique (LAM) a, aj,/ nd Oj refer to fraction of chain units in the perfect crystals, interfacial region, and amorphous region, respectively of a lamella. 

A standard Raman or infrared microspectrometer consists of an excitation source, a compound microscope, a spectrometer, and a detector. As in bulk techniques, the design of microspectroscopic experiments is guided by the sample composition as well as demands for frequency response, sensitivity, data acquisition rates, and spectral resolution. Factors specific to vibrational microspectroscopy include the spatial resolution and the optical throughput between the microscope and the spectrometer. 

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