Infrared emission spectroscopy applications

Infrared emission spectroscopy can be used for the laboratory study of heated samples as one would encounter in pyrot reactions or in the detonation of primary expls. One difficulty associated with the measurement of emission spectra of condensed phase samples is that the temp of the sample has to be uniform, or else radiation emitted from elements situated below the surface will be absorbed by the cooler particles near the surface. Emission spectrometry finds application in the study of flames and smoke... 

When the spectral characteristics of the source itself are of primary interest, dispersive or ftir spectrometers are readily adapted to emission spectroscopy. Commercial instruments usually have a port that can accept an input beam without disturbing the usual source optics. Infrared emission spectroscopy at ambient or only moderately elevated temperatures has the advantage that no sample preparation is necessary. It is particularly applicable to opaque and highly scattering samples, anodized and painted surfaces, polymer films, and atmospheric species (135). The Voyager interferometric spectrometer (IRIS) spectra from the outer planets demonstrated the analytical capabilities of ftir emission spectroscopy. As an example of industrial... 

There was also described and discussed the relatively new Fourier transform infrared emission spectroscopy (IRES), its principle, an appropriate FT-IRES setup and applications. FT-IRES is unique in that it does not require an external radiation source, because the sample itself is the source. The radiation emitted from the sample is collected and sent to the detector. The ratio of the sample signal to that from a black body source represents the spectrum. However, appli-... 

Becaii.se of the phenomenon of self-absorption the ideal sample for conventional emission studies is a thin layer (e.g.. a polymer film), on both metal and semiconductor. surfaces [81]. A sample is usually heated from below the emitting surface, the lower surface thus having a higher temperature than the upper one. Therefore, radiation emitted from below the upper surface is absorbed before it reaches the surface, and this self-absorption of previously emitted light severely truncates and alters features in the emission spectra of optically thick samples. This problem is overcome by using a laser for controlled heat generation within a thin surface layer of the sample, self-absorption of radiation thus being minimized. These methods, known as laser-induced thermal emission (LITE) spectroscopy [85], [86] and transient infrared emission spectroscopy (TIRES) [87], [88] can produce analytically useful emission spectra from optically thick samples. Quantitative applications of infrared emission spectroscopy are described in [89]-[91]. 

An overview of the application of infrared emission spectroscopy to solid materials is available [502]. 

Jones and McClelland have demonstrated the application of transient infrared emission spectroscopy (TIRES) to quantitative compositional analysis of ethylene-vinyl acetate copolymers. Standard errors are less than 1%. 

In principle, emission spectroscopy can be applied to both atoms and molecules. Molecular infrared emission, or blackbody radiation played an important role in the early development of quantum mechanics and has been used for the analysis of hot gases generated by flames and rocket exhausts. Although the availability of FT-IR instrumentation extended the application of IR emission spectroscopy to a wider array of samples, its applications remain limited. For this reason IR emission is not considered further in this text. Molecular UV/Vis emission spectroscopy is of little importance since the thermal energies needed for excitation generally result in the sample s decomposition. 

Usually, when referring to infrared spectroscopy, IR absorption spectroscopy is meant. Although this is the dominant method, occasionally it can be useful for sensing applications to also use IR emission spectroscopy. 

An introductory manual that explains the basic concepts of chemistry behind scientific analytical techniques and that reviews their application to archaeology. It explains key terminology, outlines the procedures to be followed in order to produce good data, and describes the function of the basic instrumentation required to carry out those procedures. The manual contains chapters on the basic chemistry and physics necessary to understand the techniques used in analytical chemistry, with more detailed chapters on atomic absorption, inductively coupled plasma emission spectroscopy, neutron activation analysis, X-ray fluorescence, electron microscopy, infrared and Raman spectroscopy, and mass spectrometry. Each chapter describes the operation of the instruments, some hints on the practicalities, and a review of the application of the technique to archaeology, including some case studies. With guides to further reading on the topic, it is an essential tool for practitioners, researchers, and advanced students alike. 

NMR) [24], and Fourier transform-infrared (FT-IR) spectroscopy [25] are commonly applied methods. Analysis using mass spectrometric (MS) techniques has been achieved with gas chromatography-mass spectrometry (GC-MS), with chemical ionisation (Cl) often more informative than conventional electron impact (El) ionisation [26]. For the qualitative and quantitative characterisation of silicone polyether copolymers in particular, SEC, NMR, and FT-IR have also been demonstrated as useful and informative methods [22] and the application of high-temperature GC and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) is also described [5]. 

Modern infrared (IR) spectroscopy is a versatile tool applied to the qualitative and quantitative determination of molecular species of all types. Its applications fall into three categories based on the spectral regions considered. Mid-IR (MIR) is by far the most widely used, with absorption, reflection, and emission spectra being employed for both qualitative and quantitative analysis. The NIR region is particularly used for routine quantitative determinations in complex samples, which is of interest in agriculture, food and feed, and, more recently, pharmaceutical industries. Determinations are usually based on diffuse reflectance measurements of untreated solid or liquid samples or, in some cases, on transmittance studies. Far-IR (FIR) is used primarily for absorption measurements of inorganic and metal-organic samples. 

Fourier transform methods have revolutionized many fields in physics and chemistry, and applications of the technique are to be found in such diverse areas as radio astronomy [52], nuclear magnetic resonance spectroscopy [53], mass spectroscopy [54], and optical absorption/emission spectroscopy from the far-infrared to the ultraviolet [55-57]. These applications are reviewed in several excellent sources [1, 54,58], and this section simply aims to describe the fundamental principles of FTIR spectroscopy. A more theoretical development of Fourier transform techniques is given in several texts [59-61], and the interested reader is referred to these for details. 

Results of a comprehensive study of the absolute spectral radiance of the infrared emissions from methane—air expins have been reported (Ref 44). The spectral growth of these expanding flames was recorded with a time resolution of one msec in the spectral range 1.7— 5.0 microns. Time resolved spectra were obtained as a function of stoichiometry, nitrogen dilution and Halon dilution. Similar data are also available for coal dust-air explns. Additional applications of rapid scan IR spectroscopy are discussed in Ref 50. In this work, flare spectra (Mk45, LUU-2B and LUU-2B/B) in the 1.7-4.7 and 9—14 micron regions were studied. The Mk-45 and LUU-2B/B showed similar spectral character with Na and C02 emissions superimposed on a gray body continuum, while LUU-2B flares demonstrated variable emittance properties... 

I venture to say that the majority of practical chemometrics applications in analytical chemistry are in the area of instrument specialization. The need to improve specificity of an analyzer depends on both the analytical technology and the application. For example, chemometrics is often applied to near-infrared (NIR) spectroscopy, due to the fact that the information in NIR spectra is generally non-specific for most applications. Chemometrics may not be critical for most ICP atomic emission or mass spectrometry applications because these techniques provide sufficient selectivity for most applications. On the other hand, there are some NIR applications that do not require chemometrics (e.g. many water analysis applications), and some ICP and mass spectrometry applications are likely where chemometrics is needed to provide sufficient selectivity. 

Spectrophotometers came into widespread use beginning around 1940, and this led to wide application in petroleum analysis. Ultraviolet absorption spectroscopy, infrared spectroscopy, mass spectrometry, emission spectroscopy, and nuclear magnetic resonance spectroscopy continue to make major contributions to petroleum analysis. 

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. 

Industrial Analysis with Vibrational Spectroscopy 5 Ionization Methods in Organic Mass Spectrometry 6 Quantitative Millimetre Wavelength Spectrometry 7 Glow Discharge Optical Emission Spectroscopy A Practical Guide 8 Chemometrics in Analytical Spectroscopy, 2nd Edition 9 Raman Spectroscopy in Archaeology and Art History 10 Basic Chemometric Techniques in Atomic Spectroscopy 11 Biomedical Applications of Synchrotron Infrared Microspectroscopy 12 Microwave Induced Plasma Analytical Spectrometry 13 Basic Chemometric Techniques in Atomic Spectroscopy, 2" Edition... 

McKelvie, 2008). Detection methods have included UV/Vis spectroscopy (the largest number of applications for its robustness, versatility, simplicity, and low cost), luminescence and chemiluminescence (CL) (which offer low detection limits and high sensitivity, being therefore especially favored for biological, biochemical, and trace analysis), atomic absorption and emission spectroscopy (which benefit enormously from automated sample pretreatment, used for matrix removal and analyte accumulation), electrochemistry (pH, fluoride ion selective electrodes, stripping voltammetry and conductivity), turbidimetry, vibrational spectroscopy (Fourier transform infrared spectroscopy [FTIR] and Raman) and mass spectrometry. 

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