Optical spectrometry

We often call the UV/visible and IR regions of the spectrum the optical region. Even though the optic nerve is responsive only to visible radiation, the other regions are included because the lenses, mirrors, prisms, and gratings used are similar and function in a comparable manner. Spectroscopy in the UV/visible and IR regions is, therefore, often called optical spectroscopy. 

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Table 8.76 shows the main characteristics of voltammetry. Trace-element analysis by electrochemical methods is attractive due to the low limits of detection that can be achieved at relatively low cost. The advantage of using standard addition as a means of calibration and quantification is that matrix effects in the sample are taken into consideration. Analytical responses in voltammetry sometimes lack the predictability of techniques such as optical spectrometry, mostly because interactions at electrode/solution interfaces can be extremely complex. The role of the electrolyte and additional solutions in voltammetry are crucial. Many determinations are pH dependent, and the electrolyte can increase both the conductivity and selectivity of the solution. Voltammetry offers some advantages over atomic absorption. It allows the determination of an element under different oxidation states (e.g. Fe2+/Fe3+). 

The feasibility of an optical fiber system was demonstrated for the differential absorption analysis of the car pollutant nitrogen dioxide. It absorbs in the visible and can be "sensed" using an Ar-ion laser27. The yellow metabolite bilirubin has been monitored in blood via fiber optic spectrometry in serum28. The tip of a fiber optic cable was inserted into a injection needle so to reach the blood sample, and absorbance (and later fluorescence) was acquired of a sample contained in the cavity at the tip of the fiber or needle. 

Most commercial flue gas analyzers use electrochemical cells and optical spectrometry. Because of the high temperature and dusty and harsh environment these... 

Brown, M. A. and Blin-Stoyle, A. E. (1959). Spectrographic analysis of British Middle and Late Bronze Age finds (including reprint of A sample analysis of British Middle and Late Bronze Age material, using optical spectrometry , from Proceedings of the Prehistoric Society.) Supplement to Archaeometry 2. 

Obsidian is a volcanic glass frequently used as tool by prehistoric men. The thickness of the hydration layer that has developed on the surface of the artifact since it was made can be used to date it. Measurement of the hydration layer is carried out by a variety of instrumental techniques. Among them are nuclear resonance reactions, LM, PAS, XPS, XANES, sputter-induced optical spectrometry (SIPS), and SIMS [70]. 

For these techniques, a dissolved sample is usually employed in the analysis to form a liquid spray which is delivered to an atomiser e.g. a flame or electrically generated plasma). Concerning optical spectrometry, techniques based on photon absorption, photon emission and fluorescence will be described (Section 1.2), while for mass spectrometry (MS) particular attention will be paid to the use of an inductively coupled plasma (TCP) as the atomisation/ionisation source (Section 1.3). The use of on-line coupled systems to the above liquid analysis techniques such as flow injection manifolds and chromatographic systems will be dealt with in Section 1.4 because they have become commonplace in most laboratories, opening up new opportunities for sample handling and pretreatment and also to obtain element-specific molecular information. 

Figure 1.5 Schematics of basic components of analytical techniques based on atomic optical spectrometry, (a) Atomic absorption spectrometry (b) atomic fluorescence spectrometry (c) atomic emission spectrometry.

This section starts with a discussion of selectivity for the most extended analytical atomic techniques based on optical spectrometry. Then, aspects such as detection limits (DLs), linear ranges, precision, versatility and sample throughput will be presented. The section ends with a brief comparison of the... 

Comparative Analytical Assessment of the Most Common Analytical Techniques Based on Optical Spectrometry... 

Table 1.1 Comparative advantages and limitations of the most common atomic workhorses of dissolved samples analysis by optical spectrometry.

Fourier transform infrared spectroscopy glow discharge mass spectrometry glow discharge optical spectrometry high energy electron diffraction high vacuum... 

To measure the gas phase speciation, the choice of optical spectrometries was made. These online techniques allow concentration measurements (Hartmann, 2009) and then partial pressures measurements without altering the gas phase composition. 

To contain the corrosive and concentrated mixtures, to allow gas phase speciation using optical spectrometries, two experimental devices were designed a low-pressure one, and a high-pressure one. 

STUDY OF THE HYDROLYSIS REACTION OF THE COPPER-CHLORIDE HYBRID THERMOCHEMICAL CYCLE USING OPTICAL SPECTROMETRIES... 

Study of the hydrolysis reaction of the copper-chloride hybrid thermochemical cycle using optical spectrometries... 

For a better control of the kinetics of the reactions, the use of optical spectrometries is proposed. 

Manipulation of the sample once it is loaded is not readily achieved. It would be desirable, for example, to hold the sample stationary if supplementary observations are to be made of the surface by x-ray diffraction or optical spectrometry. It is possible that ferromagnetic samples may be lined up by the application of a suitably oriented magnetic field, but efforts to achieve this have so far not been too successful. The placing of temporary arrests around the sample has also been found to be inadvisable because of the difficulty of not injuring the hang-down connections. 

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