Spectroscopy, optical emission

Optical emission spectroscopy is routinely used for the determination of nitro-gen-15. The method depends upon the wavelength separation of the isotopic species of nitrogen gas ( N2, and due to the isotopic shift. 

Infrared spectroscopy has limited applications in the detection and assay of labelled compounds. Absorption peaks at 2193 cm for carbon monoxide- C and at 2144 cm for CO are sufficiently separated to determine the isotope ratio [139]. With C contents ranging from 1 to 20 atom%, the mean error quoted was about 2% and had a relative standard deviation of about 6%. [Car-Z on Z- C] acetophenone gives a peak in the infrared spectrum at 1685 cm whUe the (carbo/y /- Cyiabelled compound has a corresponding absorption at 1645 cm [128]. In certain cases it is therefore possible to utilise published data for a rapid assay of labelled compounds. Infrared data on C- and N-labelled compounds have been reviewed [140]. 

Although as yet not widely used, the possibility of using Raman scattering for measuring isotope ratios has been investigated. It has been demonstrated that 

Activation analysis is another technique that has found some applications. In these methods, the desired stable isotope is made to undergo a suitable nuclear reaction. The parent isotope is determined by measurement of the resulting nuclide. As an example, the 0 content of water samples as small as 1.S jul has been determined by charged particle activation [142]. 

3 TECHNIQUES BASED ON OPTICAL WAVELENGTHS 2.3.1 Optical Emission Spectroscopy 

2 Simultaneous ICP-OES. The simultaneous ICP-OES measures all elements at the same time. A large number of samples can be analysed in a short period of time making it useful for rapid analysis. They are very expensive and are used where routine multiple sample analysis is required on a regular basis, usually on the same elements and samples. Most simultaneous instruments are custom designed for a selection of elements at specific wavelengths and some instruments can have between 10 and 100 slits and are factory fixed for selected elements. Typical applications would be in the water industries where analysis for metal content would be important for health reasons, in the water supply to power stations where analysis is usually carried out before and after treatment prior to use so as to avoid contamination of turbine blades, in the food industries, in mineral exploration or any other routine analysis where metal analysis requirements do 

Trace analysis requiring background correction can usually be achieved by computer control displacement of the entrance slit or by rotation of a quartz refractor plate behind the entrance slit. Using this technique allows the application of slew scan methods which allow scans from different samples to be superimposed with solutions of samples, dissolution solvent(s), etc. 

A Practical Approach to Quantitative Metal Analysis of Organic Matrices 

---

Analyses of alloys or ores for hafnium by plasma emission atomic absorption spectroscopy, optical emission spectroscopy (qv), mass spectrometry (qv), x-ray spectroscopy (see X-ray technology), and neutron activation are possible without prior separation of hafnium (19). Alternatively, the combined hafnium and zirconium content can be separated from the sample by fusing the sample with sodium hydroxide, separating silica if present, and precipitating with mandelic acid from a dilute hydrochloric acid solution (20). The precipitate is ignited to oxide which is analy2ed by x-ray or emission spectroscopy to determine the relative proportion of each oxide. 

Aluminum is best detected quaUtatively by optical emission spectroscopy. SoHds can be vaporized direcdy in a d-c arc and solutions can be dried on a carbon electrode. Alternatively, aluminum can be detected by plasma emission spectroscopy using an inductively coupled argon plasma or a d-c plasma. Atomic absorption using an aluminum hoUow cathode lamp is also an unambiguous and sensitive quaUtative method for determining alurninum. 

Tungsten is usually identified by atomic spectroscopy. Using optical emission spectroscopy, tungsten in ores can be detected at concentrations of 0.05—0.1%, whereas x-ray spectroscopy detects 0.5—1.0%. ScheeHte in rock formations can be identified by its luminescence under ultraviolet excitation. In a wet-chemical identification method, the ore is fired with sodium carbonate and then treated with hydrochloric acid addition of 2inc, aluminum, or tin produces a beautiful blue color if tungsten is present. 

Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES)... 

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

Elastic Recoil Detection Analysis Glow discharge mass spectrometry Glow discharge optical emission spectroscopy Ion (excited) Auger electron spectroscopy Ion beam spectrochemical analysis... 

Edited by H. Bubert and H. Jenett Copyright 2002 Wiley-VCH Verlag GmbH ISBNs 3-527-30458-4 (Hardback) 3-527-60016-7 (Electronic) 4.4 Clow Discharge Optical Emission Spectroscopy (CD-OESj... 

Clow Discharge Optical Emission Spectroscopy (CD-OESj 223... 

Chw Discharge Optical Emission Spectroscopy (CD-OES) 229 Tab. 4.2. Some typical applications of GD-OES depth-profile analysis. 

Until the last War, variants of optical emission spectroscopy ( spectrometry when the technique became quantitative) were the principal supplement to wet chemical analysis. In fact, university metallurgy departments routinely employed resident analytical chemists who were primarily experts in wet methods, qualitative and quantitative, and undergraduates received an elementary grounding in these techniques. This has completely vanished now. 

In order to supplement micro-mechanical investigations and advance knowledge of the fracture process, micro-mechanical measurements in the deformation zone are required to determine local stresses and strains. In TPs, craze zones can develop that are important microscopic features around a crack tip governing strength behavior. For certain plastics fracture is preceded by the formation of a craze zone that is a wedge shaped region spanned by oriented micro-fibrils. Methods of craze zone measurements include optical emission spectroscopy, diffraction... 

In order to relate material properties with plasma properties, several plasma diagnostic techniques are used. The main techniques for the characterization of silane-hydrogen deposition plasmas are optical spectroscopy, electrostatic probes, mass spectrometry, and ellipsometry [117, 286]. Optical emission spectroscopy (OES) is a noninvasive technique and has been developed for identification of Si, SiH, Si+, and species in the plasma. Active spectroscopy, such as laser induced fluorescence (LIF), also allows for the detection of radicals in the plasma. Mass spectrometry enables the study of ion and radical chemistry in the discharge, either ex situ or in situ. The Langmuir probe technique is simple and very suitable for measuring plasma characteristics in nonreactive plasmas. In case of silane plasma it can be used, but it is difficult. Ellipsometry is used to follow the deposition process in situ. 

Knowledge on the plasma species can be obtained by the use of plasma diagnostics techniques, such as optical emission spectroscopy (OES) and mass spectroscopy (MS). Both techniques are able to probe atomic and molecular, neutral or ionized species present in plasmas. OES is based on measuring the light emission spectrum that arises from the relaxation of plasma species in excited energy states. MS, on the other hand, is generally based on the measurement of mass spectra of ground state species. 

Danzer K, Wagner M (1993) Multisignal calibration in optical emission spectroscopy. Fresenius J Anal Chem 346 520... 

Optical emission spectroscopy by grating instruments by prism instruments by Quantometers 200,000 10,000 60... 

Optical elements, liquid crystalline materials in, 15 116—117 Optical emission spectra, 14 833-837 plutonium, 19 671—673 Optical emission spectroscopy (OES), archaeological materials, 5 742 Optical fiber(s), 13 391-392 24 618 defects in, 11 145 drawing of, 11 141-145 fabrication of, 11 135-141 health care applications for, 13 397 overcladding of, 11 144 remote measurements using, 14 234 in sensors, 22 270-271 sol-gel processing of, 11 144-145 strength of, 11 141-145 vitreous silica in, 22 444 Optical fiber sensors, 12 614-616 Optical germanium, 12 556... 

---