Kinetic spectrophotometry

Hodgson B W and Keene J P 1972 Some characteristics of a pulsed xenon lamp for use as a light source in kinetic spectrophotometry Rev. Sol. Instnim. 43 493-6... 

Concise reviews of pertinent aspects of thermodynamics, kinetics, spectrophotometry, etc. are presented prior to developing applications of these topics to polymers. 

For detection residue amounts of tetracyclines in dairy products widely used methods FIPLC, immunoaffinity chromatography, kinetic spectrophotometry, which are expensive and complicated. 

Fermi golden rule, 268 Filipescu, N., 291 Fisch, M. H., 307 Fischer, F., 379 Flash photolysis, 80-92 of aromatic hydrocarbons, 89, 90 determination of jsc, 228-230 determination of triplet lifetime, 240-242 energy of higher triplet levels, 219-220 flash kinetic spectrophotometry, 82, 83 measurement of triplet spectra, 81,82 nanosecond flash kinetic apparatus, 89 nanosecond flash spectrographic apparatus, 88... 

Adapted from W.G. Herkstroeter and G.S. Hammond, Energy transfer study by kinetic spectrophotometry , Journal of the American Chemical Society, Volume 88. American Chemical Society... 

Selected entries from Methods in Enzymology [vol, page(s)] Absorption spectroscopy, 24, 3 flash kinetic spectrophotometry, 24, 25 ion transport (H+, K+, exchange phenomena), 24,... 

Although its precise structure has not yet been settled, the hydrated electron may be visualized as an excess electron surrounded by a small number of oriented water molecules and behaving in some ways like a singly charged anion of about the same size as the iodide ion. Its intense absorption band in the visible region of the spectrum makes it a simple matter to measure its reaction rate constants using pulse radiolysis combined with kinetic spectrophotometry. Rate constants for several hundred different reactions have been obtained in this way, making kinetically one of the most studied chemical entities. 

Figure 10.10 Instrumentation for flash photolysis. (A) Flash spectroscopy (B) flash kinetic spectrophotometry.

Zhao, Y.X. and Dong, Y.H. (2003) Study on kinetic spectrophotometry determination of trace lead. Fenxi Kexue Xuebao, 19 (6), 573-575. 

Two dosimeters suitable for monitoring single pulses of x-rays with doses in the range 1 to 100 rads at dose rates greater than 103 rads/sec. are described. Both systems were independently referred to Fricke dosimetry as the absolute standard and cross checked under pulse conditions. In one system the transient hydrated electron absorption produced by the pulse is measured by kinetic spectrophotometry as an indication of the dose. In the other, doped LiF crystals of about 50 mg. are irradiated in sealed polyethylene bags under conditions of electronic equilibrium. Readout of the irradiated crystals was done on a standard commercial machine. Both methods were readily capable of 5% precision and with a little care better than 3% is obtainable. 

The majority of laboratories using the pulse radiolysis technique use the method of kinetic spectrophotometry to detect and measure radiation-induced changes. With such apparatus it is thus possible to use transient as well as permanent optical changes as a measure of the effects of a radiation pulse. A convenient transient absorption is the hydrated electron (6, 11) which has the very high extinction coefficient of 1.85 X 104 cm."1 at 7000 A. Use of the hydrated electron as a dosimeter has already been discussed (4,9), and it has found widespread use among workers in pulse radiolysis as an approximate dosimeter. This work set out to measure the parameters under which the hydrated electron could be used as an accurate dosimeter for low dose pulses. As the amount of hydrated electron present at the end of the irradiation pulse is used as a measure of dose, it is important that the lifetime of the e aq is long compared with the pulse length. 

Qumones are capable of reacting with a large number of radiation-produced primary species like eaq, H and OH [14-16]. While eaq and H may reduce quinones by one-electron reduction process to the semiquinone, OH may either add to the ring or some suitable substituent position and give rise to one-electron oxidation to some form of transient. Formation of semiquinones by y-radiolysis has been discussed in detail m earlier monographs [7,9,17-19] and will not be included here. Pulse radiolysis kinetic spectrophotometry technique [20,21] has opened up new scope for detailed studies [8-12,15,16,22-25] on semiquinones. On pulse radiolytic one-electron reduction of quinones, semiquinones may be formed as follows -... 

The purpose of this study is to explore the fate of OH radicals and the identity and chemistry of their progeny in seawater. This paper presents some of the experimental evidence concerning radical formation and behavior in seawater and artificial seawater obtained by the fast-reaction kinetics technique of flash photolysis-kinetic spectrophotometry (4) supplemented by pulse radiolysis ( ). The companion paper which follows presents results on related reactions and rates observed in media simpler than seawater and applies them to partially explain the data reported here using a simple reaction-mechanistic model. 

Zafiriou, 0. C. True. M. B. Flash photolysis - kinetic spectrophotometry of seawater and related solutions Data acquisition, processing, and validation," UHOI Tech. Memo. 1-77, Woods Hole Oceanographic Institution, 1977. 

Xu, H. He, P. Studies on speciation analysis and distribution of selenium in marine organisms by catalytic kinetic spectrophotometry. Haiyang Kexue 2094, 28, 36-39 Chem. Abstr. 2005,144, 56704. 

Figure 4.2 Microsecond flash apparatus, (a) Schematic diagram of apparatus for microsecond flash spectropho-tography. (b) Schematic diagram of apparatus for microsecond flash kinetic spectrophotometry. After Ref. [2,b].

In the microsecond time range, several other monitoring techniques besides those of kinetic spectrophotometry can be used [9]. Conductivity methods may be useful where charged particles are involved, especially where changes of absorbance are small they are even more sensitive than spectrophotometry, and can be used for times down to picoseconds. Fast polarography, by pulse techniques, which monitor current-time curves immediately... 

Figure 4.9 Nanosecond kinetic spectrophotometry, (a) Arrangement for nanosecond kinetic spectrophotometry. After G. Porter and M.A. West, Ref. [2,b, Figure 10.40]. (b) Oscilloscope traces of transient decay a, 1,2-benzanthracene singlet decaying into the triplet in polymethylmethacrylate solution b, phenazine triplet decay in cyclohexane. Horizontal scale a, 100 ns per division b, 200 ns per division. Vertical scale transmitted monitoring light intensity. From L. Patterson and G. Porter, Ref. [12,h].

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