Luminescence analysis

As mentioned above, the interpretation of CL cannot be unified under a simple law, and one of the fundamental difficulties involved in luminescence analysis is the lack of information on the competing nonradiative processes present in the material. In addition, the influence of defects, the surface, and various external perturbations (such as temperature, electric field, and stress) have to be taken into account in quantitative CL analysis. All these make the quantification of CL intensities difficult. Correlations between dopant concentrations and such band-shape parameters as the peak energy and the half-width of the CL emission currently are more reliable as means for the quantitative analysis of the carrier concentration. 

R. J. Hurtubise. Solid Surface Luminescence Analysis. Marcel Dekker, New York, 1981. Practical aspects of analysis for organics adsorbed onto solids. 

Gleitzer C, Goodenough JB (1985) Mixed-Valance Iron Oxides. 61 1-76 Gliemann G, Yersin H (1985) Spectroscopic Properties of the Quasi One-Dimensional Tetracyanoplatinate(II) Compounds. 62 87-153 Golovina AP, Zorov NB, Runov VK (1981) Chemical Luminescence Analysis of Inorganic substances. 47 53-119... 

The immense growth in the luminescence literature during the period between these two reviews had little to do with developments in fundamental theory. It was mainly due to the availability of new instrumentation, such as the photomultiplier (around 1950), the laser (around 1960), transistor and microcircuit electronics (around 1970), and ready access to laboratory computers (around 1975). All aspects of luminescence theory now being used to interpret luminescence measurements have been known since the early 1900 s and nearly all of the types of measurements now being made had been initiated with cruder techniques by 1930. We discuss here many of the latest techniques in luminescence analysis with selected highlights from the historical development of luminescence and a look at several recent developments in luminescence applications that appear likely to be important to future research. 

Applications and Interactions in Solid-Surface Luminescence Analysis... 

Solid-surface room-temperature phosphorescence (RTF) is a relatively new technique which has been used for organic trace analysis in several fields. However, the fundamental interactions needed for RTF are only partly understood. To clarify some of the interactions required for strong RTF, organic compounds adsorbed on several surfaces are being studied. Fluorescence quantum yield values, phosphorescence quantum yield values, and phosphorescence lifetime values were obtained for model compounds adsorbed on sodiiun acetate-sodium chloride mixtures and on a-cyclodextrin-sodium chloride mixtures. With the data obtained, the triplet formation efficiency and some of the rate constants related to the luminescence processes were calculated. This information clarified several of the interactions responsible for RTF from organic compounds adsorbed on sodium acetate-sodium chloride and a-cyclodextrin-sodium chloride mixtures. Work with silica gel chromatoplates has involved studying the effects of moisture, gases, and various solvents on the fluorescence and phosphorescence intensities. The net result of the study has been to improve the experimental conditions for enhanced sensitivity and selectivity in solid-surface luminescence analysis. 

Solid-surface luminescence analysis involves the measurement of fluorescence and phosphorescence of organic compounds adsorbed on solid materials. Several solid matrices such as filter paper, silica with a polyacrylate binder, sodium acetate, and cyclodextrins have been used in trace organic analysis. Recent monographs have considered the details of solid-surface luminescence analysis (1,2). Solid-surface room-temperature fluorescence (RTF) has been used for several years in organic trace analysis. However, solid-surface room-temperature phosphorescence (RTF) is a relatively new technique, and the experimental conditions for RTF are more critical than for RTF. 

Since publication of these two studies (15,16), several researchers have used solid-surface luminescence analysis in trace organic analysis (1,2). 

Recent Uses of Solid-Surface Luminescence Analysis in Environmental Analysis. Vo-Dinh and coworkers have shown very effectively how solid-surface luminescence techniques can be used for environmentally important samples (17-22). RTF has been used for the screening of ambient air particulate samples (17,18). In addition, RTF has been employed in conjunction with a ranking index to characterize polynuclear aromatic pollutants in environmental samples (19). A unique application of RTF reported recently is a personal dosimeter badge based on molecular diffusion and direct detection by RTF of polynuclear aromatic pollutants (20). The dosimeter is a pen-size device that does not require sample extraction prior to analysis. 

Interactions in Solid-Surface Luminescence Temperature Variation. Solid-surface luminescence analysis, especially solid-surface RTF, is being used more extensively in organic trace analysis than in the past because of its simplicity, selectivity, and sensitivity (,1,2). However, the interactions needed for strong luminescence signals are not well understood. In order to understand some of the interactions in solid-surface luminescence we recently developed a method for the determination of room-temperature fluorescence and phosphorescence quantum yields for compounds adsorbed on solid surfaces (27). In addition, we have been investigating the RTF and RTF properties of the anion of p-aminobenzoic acid adsorbed on sodium acetate as a model system. Sodium acetate and the anion of p-aminobenzoic acid have essentially no luminescence impurities. Also, the overall system is somewhat easier to study than compounds adsorbed on other surfaces, such as filter paper, because sodium acetate is more simple chemically. 

Solid-surface luminescence analysis is a useful approach for organic trace analysis because of its simplicity, sensitivity, and selectivity. It will continue to be used in environmental analysis and other areas not only for the reasons mentioned above but also because it is readily adaptable to field work. By developing a fundamental understanding of the interactions responsible for strong RTF and RTF signals, the advantages and disadvantages of the luminescence approach will be more specifically defined in the future. 

TGA, iodometric, mid-IR, luminescence (fluorescence and phosphorescence) and colour formation (yellowness index according to standard method ASTM 1925) were all employed in a study of aspects of the thermal degradation of EVA copolymers [67], Figure 23 compares a set of spectra from the luminescence analysis reported in this work. In the initial spectra (Figure 23(a)) of the EVA copolymer, two excitation maxima at 237 and 283 nm are observed, which both give rise to one emission spectrum with a maximum at 366 nm weak shoulders... 

Vo-Dinh T., Miller G.H., Bello J., Johnson R., Moody R.L., Alak A., Fletcher W. R., Surface-active substrates for Raman and luminescence analysis, Talanta 1989 36 227-234. 

Rapid method for the detn of N content in NC s by the ferrous ammonium sulfate method, using as the "standard a NC of known N content, previously detd by nitrometer) 19)K.Thinius, Farbe u Lack 56, 3-9(1950) CA 44, 4817 (1950)(Luminescence analysis for indentification of NC, cellulose, cellulose acetate, ethylcellulose methylcellulose) 20)L.B.Genung, AnalChem 22, 403(1950) CA 44, 6l21(1950)(Detn of N content by nitrometer) 21)R.Leclercq J. 

Fluorescence spectrometry forms the majority of luminescence analysis. However, the recent developments in instrumentation and room temperature phosphorescence techniques have given rise to practical and fundamental advances which should increase the use of phosphorescence spectrometry. The sensitivity of phosphorescence is comparable to that of fluorescence and complements the latter by offering a wider range of molecules of study... 

Note Typical metallic complexes are those of l,8-naphthyridine-2,7-dicar-boxylic acid with Ni,368 Rh,498 and Ru 498 and of 2,7-bis[jV, (V-di(carbox-ymethyl)aminomethyl]-l,8-naphthyridine (14) with Eu and Tb (for luminescence analysis).714... 

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