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Chemiluminescent emission spectroscopy

Another method of measuring the relative quantum yield of the radical decomposition process (eq. 22) was also devised recently (144). This involves HNO chemiluminescence photoexcitation spectroscopy. When an H atom recombines with an NO molecule, an electronically excited HN0 ( A A" ) is formed. Fluorescence emission from HNO occurs at 762 nm. The HNO chemiluminescence in a low-pressure 1 10 mixture of H2CO and NO is proportional to the H-atom quantum yield from the photolysis of H2CO. The photoexcited HNO (red) chemiluminescence excitation spectrum of a H2CO/NO mixture obtained with a tunable laser at high resolution is shown in Fig. 2 together with an absorption spectrum and a H2CO fluorescence (blue) excitation spectrum (237). The relevant reaction scheme is as follows ... [Pg.21]

Figure 24-4 illustrates the processes involved in emission and chemiluminescence spectroscopy. Here, the analyte is stimulated by heat or electrical energy or by a chemical reaction. Emission spectroscopy usually involves methods in which the stimulus is heat or electrical energy, while chemiluminescence spectroscopy refers to excitation of the analyte by a chemical reaction. In both cases, measurement of the radiant power emitted as the analyte returns to the ground state can give information about its identity and concentration. The results of such a measurement are often expressed graphically by a spectrum, which is a plot of the emitted radiation as a function of frequency or wavelength. [Pg.715]

Chemically modified celluloses have been analyzed by conventional wet methods and by various Instrumental methods designed to differentiate bulk and surface properties. Electron emission spectroscopy for chemical analyses (ESCA) used alone and In combination with radiofrequency cold plasmas yielded elemental analyses, oxidative states of the element, and distribution of the element. Techniques of electron paramagnetic resonance (EPR), chemiluminescence, reflectance infrared spectroscopy, electron microscopy, and energy dispersive X-ray analyses were also used to detect species on surfaces and to obtain depth profiles of a given reagent in chemically modified cottons. [Pg.3]

McCord P, Yau S-L, Bard AJ (1992) Chemiluminescence of anodized and etched sihcon evidence for a luminescent siloxene-like layer on porous silicon. Science 257 68-69 Mikulec FV, Kirtland JD, Sailor MJ (2002) Explosive nanocrystalline porous silicon and its use in atomic emission spectroscopy. Adv Mater 14 38-41 Parimi VS, Tadigadapa SA, Yetter RA (2012) Control of nanoenergetics through organized micro-stmctures. J Micromech Microeng 22 055011(1-6)... [Pg.189]

Emission spectroscopy and chemiluminescence spectroscopy differ from the other types in that no e, -ternal radiation source is required the sample itself is the emitter (see Figure 7-lc). In emission spectroscopy. the sample container is a plasma, a spark, or a dame that both contains the sample and causes it to... [Pg.619]

Other possible simultaneous techniques in combination with CL are /zFTIR, FTIES and oxygen uptake. Simultaneous FTIES-CL analysis (both emission spectroscopies) has been used to evaluate oxidation models for polypropylene [598]. In a further instrumental advancement, imaging chemiluminescence (ICL) has become available cfr. Chp. 5.6.4.1). Early stages of polymer oxidation can also be studied using 02 exposure and ToF-SIMS analysis [599,600]. [Pg.89]

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. [Pg.41]

A new generation of element selective detectors has become available based on chemiluminescence and plasma emission spectroscopy that have excellent sensitivity, uniformity of response, and selectivity over carbon. [Pg.25]

Materials characterization techniques, ie, atomic and molecular identification and analysis, ate discussed ia articles the tides of which, for the most part, are descriptive of the analytical method. For example, both iaftared (it) and near iaftared analysis (nira) are described ia Infrared and raman SPECTROSCOPY. Nucleai magaetic resoaance (nmr) and electron spia resonance (esr) are discussed ia Magnetic spin resonance. Ultraviolet (uv) and visible (vis), absorption and emission, as well as Raman spectroscopy, circular dichroism (cd), etc are discussed ia Spectroscopy (see also Chemiluminescence Electho-analytical techniques It unoassay Mass specthot thy Microscopy Microwave technology Plasma technology and X-ray technology). [Pg.393]

Spectroscopy, aimual reviews of new analytical instmmentation from the Pittsburgh Conference on Analytical Chemistry and AppHed Spectroscopy. Analytical Chemisty, "Fundamental Reviews" (June 1994, June 1996), analytical appHcations of infrared, ultraviolet, atomic absorption, emission, Raman, fluorescence, phosphorescence, chemiluminescence, and x-ray spectroscopy. [Pg.326]

In general, gas chromatography will undoubtedly continue to be the method of choice for characterization of light hydrocarbon materials. New and improved detection devices and techniques, such as chemiluminescence, atomic emission, and mass spectroscopy, will enhance selectivity, detection limits, and analytical productivity. Laboratory automation through autosampling, computer control, and data handling will provide improved precision and productivity, as well as simplified method operation. [Pg.252]

Luminescence is a well-established class of analytical spectroscopic techniques where a species emits light after excitation. Emission is an elecnonic nansition from an excited state as opposed to the ground state as is the case in most other spectroscopies. Photoluminescence, or light-induced fluorescence (LIE), is the most common route to induce emission where sufficient incident photons of a particular energy excite the target species via absorption. Although less common, nomadiative excitation can also occur via a chemical reaction termed chemiluminescence. Unless otherwise stated, the terms luminescence and fluorescence within this review infers excitation by light induction. [Pg.338]

Optical sensors have the advantage of an easily measured signal that can be seen by the naked eye in some cases. Optical detection methods include fluorescence, surface plasmon resonance spectroscopy, Raman, IR, and chemiluminescence (Fabbrizzi and Poggi 1995 deSilva et al. 1997). However, the fabrication and development of optical MIP sensors requires that a colored, emissive, or fluorescent monomer... [Pg.416]

The principal reaction discussed above forms oxygen molecules in high vibrational levels of the ground state. This is chemi-excitation but is not chemiluminescence vibration-rotation transitions of homonuclear molecules are forbidden. For such cases electronic absorption spectroscopy is the required technique. For reactions in which a heteronuclear diatomic (or a polyatomic) molecule is excited these transitions are allowed. They are overtones of the molecular transitions that occur in the near infrared. These excited products emit spontaneously. The reactions are chemiluminescent, their emission spectra may be obtained and analyzed in order to deduce the detailed course of the reaction. [Pg.127]

Whilst chemiluminescence has been observed [212] from the reactions of Sm, Eu, Yb + F2, Cl2, little is known about the thermodynamics and spectroscopy of the metal halides. The only analysis of energy partitioning amongst the electronic states of the halide products is for the reactions Yb + F2 and Yb + C102 [396], where emission is seen from the A, B and C states of the halide. [Pg.434]

Chemiluminescence has been used to measure the relative yields of excited ketones formed from self reaction of alkoxyl and alkylperoxyl radical pairs . In the photochemistry of aryl azides a dehydroazepine is detected by time resolved infra red spectroscopy and flash photolysis at room temperature . Singlet and triplet nitrenes and dehydroazepenes have also been detected in the photochemistry of 3- and 4-nitrophenyl azides . Picosecond and nanosecond laser photolysis of p-nitrophenyl acetate in aqueous media produces a triplet state of the -nitrobenzylanion and CO2 after cleavage of the rnr triplet. Absorption, emission, and reaction kinetics of dimethylsilylene produced by flash photolyses of dodecamethylcycloherasilane is another interesting study 2,... [Pg.35]

Sulfur-containing components exist in gasoline-range hydrocarbons and can be identified with a gas chromatographic capillary colunm coupled with either a sulfur chemiluminescence detector or an atomic emission detector (AED) (ASTM D-5623). The most widely specified method for total sulfur content uses X-ray spectrometry (ASTM D-2622), and other methods that use ultraviolet fluorescence spectroscopy (ASTM D-5453) and/or hydrogenolysis and colorimetry (ASTM D-4045) are also apphcable, particularly when the sulfur level is low. [Pg.118]


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